The Online Encyclopedia and Dictionary






Computer mouse

Two wireless computer mice, with scroll wheels
Two wireless computer mice, with scroll wheels

A mouse is a handheld pointing device for computers, involving a small object fitted with one or more buttons and shaped to sit naturally under the hand. The underside of the mouse houses a device that detects the mouse's motion relative to the flat surface on which it sits. The mouse's 2D motion is typically translated into the motion of a cursor on the display.

It is called a mouse primarily because the cord on early models resembled the rodent's tail, and also because the motion of the pointer on the screen can be mouselike. In popular usage, the plural can be either mice or mouses. See English plural for more information.


History of mouse engineering

The first computer mouse held by inventor Douglas Engelbart showing the wheels which directly contact the working surface.
The first computer mouse held by inventor Douglas Engelbart showing the wheels which directly contact the working surface.

The mouse was invented by Douglas Engelbart of Stanford Research Institute in 1963 after extensive usability testing. The first mouse was bulky, and used two gear wheels perpendicular to each other: the rotation of each wheel was translated into motion along one axis in the plane. Douglas Engelbart received patent US3541541 on November 17, 1970 for a "X-Y Position Indicator For A Display System".

A later variation, invented in the early 1970s by Bill English at Xerox PARC, replaced the external wheels with a single ball which could rotate in any direction. The ball's motion, in turn, was detected using perpendicular wheels housed on the interior of the mouse's body. This variant of the mouse resembled an inverted trackball, and was the predominant form used with personal computers throughout the 1980s and 1990s. Modern computer mice took form at the École Polytechnique Fédérale de Lausanne (EPFL) under the inspiration of Professor Jean-Daniel Nicoud and the hands of engineer and watchmaker André Guignard. A spin-off of EPFL, Logitech, launched the first popular mice.

Optical mice

In a separate line of evolution, the optical mouse detected movement using an optical sensor on its underside, paired with a light-emitting diode to illuminate the surface. Early optical mice, such as those invented by Steve Kirsch of Mouse Systems Corporation, could only be used on a special metallic surface (mouse pad) imprinted with a grid of fine blue and gray lines. As computing power grew cheaper, it became possible to embed more powerful special-purpose image processing chips in the mouse. This advance enabled the mouse to detect the relative motion of the mouse on a wide variety of surfaces (and in turn translating the movement of the mouse over the surface into the movement of the cursor), eliminating the need for a special mouse pad. This advance paved the way for widespread adoption of optical mice.

Modern surface-independent optical mice work by using a sensor to take successive pictures of the surface the mouse is operating on. Changes between one frame and the next are processed by the image processing part of the chip and translated into movement on the two axes. For example, the Agilent Technologies ADNS-2610 optical mouse sensor will process 1512 frames per second: each frame is a rectangular array of 18*18 pixels, and each pixel can sense 64 different levels of gray.

Advances in mouse technology is mostly driven by competetive FPS gamers, who prefer more accurate mice for more accurate aiming.

Mechanical versus optical mice

Supporters of the optical mice claim that such mice work better overall when compared to a classic mechanical mouse, that no maintenance is required and the optical mouse itself is expected to last longer than a mechanical one, due to fewer moving parts.

On the other hand, supporters of — or otherwise people feeling comfortable with — mechanical mice claim that optical mice can be totally unreliable or even useless on some surfaces, which was true for the earlier models of optical mice and even some present-day models, which have trouble working on too glossy mousepads and some specific surfaces (especially transparent ones). Cheaper optical mice also have problems tracking extremly fast movement. This problem is not present in high end optical mice which can track up to 40 inches a second. Also, when a mechanical mouse doesn't seem to work properly, all the "maintenance" it usually needs is cleaning the motion-detecting axes from the collected dirt.

A point of strength of mechanical mice lies in the field of wireless or other portable pointing devices. A wireless mechanical mouse may only draw 5mA or less of electrical current, whereas an optical mouse typically draws 25mA to power an LED or laser diode. Older optical wireless mice can draw even more current. This can result in severely reduced autonomy and need for frequent battery replacement or lengthy recharge cycles, making them unsuitable for continuous work.

Laser mice

In 2004, Logitech, along with Agilent Technologies, introduced the laser mouse. This mouse utilizes a small laser instead of the normal LED found in other optical mice. The new technology can increase the detail of the image taken by the mouse. The companies claim that this leads to a 20x increase in accuracy compared to conventional optical mice. Gamers have complained that the MX 1000 does not immediately respond to movment after it is picked up, moved, and then put down on the mouse pad.


In contrast to the motion sensing mechanism, the mouse's buttons have changed little, varying mostly in shape, number, and placement. Engelbart's very first mouse had a single button; this was soon increased to three. Commercial mice usually had between one and three buttons, although in the late 1990s some mice sprouted five or more.

Most popular are mice with two buttons. The most common purpose for the second button is to invoke a contextual menu in the interface, which contains options specifically tailored to the interface element over which the mouse was positioned. This is used by the Windows operating system in its default configuration, as well as many others.

Typical mouse with scroll wheel
Typical mouse with scroll wheel

On systems with three buttons on the mouse, pressing the center button (a "middle click") is often used as a convenience to map the action to a commonly used action, or a macro. In the X window system, middle clicking pastes the contents of the primary buffer at the cursor's position. Middle-clicks are often used as a spare button in case a function is not easily allocated.

One major innovation in mouse buttons was the scroll wheel: a small wheel, with its axis oriented parallel to the mousing surface, that could be rotated "up" or "down" to provide immediate one-dimensional input. Usually, this input was translated into "scrolling" up or down within the currently selected window. This is especially helpful in navigating a long document. The scroll wheel can often be pressed straight down, replacing the third (center) button. Doing so often activates autoscrolling in the Windows operating system if an application supports it. Some newer mouse models allow horizontal as well as vertical scrolling. Some designs make use of a "rocker" button instead of a wheel – a pivoting button that can be pressed at the top or bottom simulating up and down respectively.

Additional buttons

Five or more buttons have sometimes been built in to mice, especially ones designed for the Windows operating system. A few have included an extensive array of buttons. Depending on the user's preferences, these buttons might allow forward and backward web navigation, or scrolling through a browser's history. However, these newer functions are not supported by all software. The additional buttons are often used in computer games, where quick and easy access to a wide variety of functions (for example, weapon-switching in first-person shooters) can be very beneficial. The Apple Macintosh has always shipped with a single-button mouse, requiring users to "chord" mouse gestures by pressing a keyboard button. Despite the fact that Mac OS X has supported multi-button mice for years, Apple ships all of its new computers with single-button mice, despite the controversy. This is defended by the company as an decision meant to simplify and maintain control over the overall "look-and-feel" of the user interface.


Like all input devices, mice need some connection to the host computer in order to transmit their input. Typical mice use a thin electrical cord (e.g. an RS-232, ADB or USB cable) for this purpose. It was most likely the combination of the tail-like cord, size, and shape which led the mouse's inventors to name it as such. Cordless ("tail-less") mice use wireless communication to transmit data via infrared, radio or Bluetooth.

Common button uses

There are several methods of input using a mouse aside from the most basic moving of the device to make a cursor move.

Single clicking

This is the most common method of distinguishing mouse based input. On single-button mice this involves using the mouse's one button. On multiple-button mice, it involves any of the buttons and is usually characterized by which button is pushed (e.g. left-clicking, right-clicking). See point-and-click.

Double clicking

A double click occurs when the user presses the button twice in quick succession. This triggers an action separate from that of a single-click. For example, in the Macintosh Finder, the user single-clicked to select a file, and double-clicked in order to open that file. Usability studies have found that the double-click can be confusing and hard to use — for example, users with poor motor skills may not perform the second click fast enough, so that the action is interpreted as two single clicks rather than a double click. (Ironically, the double-click was introduced because the previous solution — separate mouse buttons for separate actions — was also found to be confusing in user studies.) Most multiple-button mice allow setting one button to emit a double-click on a single press.


A triple click occurs when the user presses the button three times in quick succession. This also triggers an action separate from that of a single-click. It is most commonly seen in word processors to select a whole paragraph and web browsers to select a whole line of text.


A user "drags" a mouse by depressing and continuing to hold down a mouse button while moving the mouse across the mousing surface. Because it involves moving the mouse in addition to clicking its buttons, dragging is a form of gesture, as described below. See drag-and-drop.

Mouse gestures

Main article: Mouse gestures

A mouse gesture is a way of combining mouse movements with clicks, which the software then recognizes as a specific command.

Tactile mice

In 2000, Logitech introduced the tactile mouse, which contained a small actuator that made the mouse vibrate. Such a mouse could be used to augment user interfaces with haptic feedback. Other unusual variants have included mice that are held freely in the hand, rather than on a flat surface, and detect six dimensions of motion (the three spatial dimensions, plus rotation on three axes). So far, these mouse exotica have not achieved widespread popularity.

Mice in the marketplace

In the 1970s, Xerox PARC included mice with its Xerox Star. Later, inspired by the Star, Apple Computer released the Apple Lisa, which also used a mouse. However, neither the Star nor the Lisa were commercially successful. Only with the release of the Apple Macintosh in 1984 did the mouse see widespread use.

The Macintosh design was influential, and its success led many other vendors to begin producing mice or including them with their other computer products. The widespread adoption of graphical user interfaces in the 1980s and 1990s made mice indispensable for computer use. By 2000, Dataquest estimated that $1.5 billion worth of mice were sold worldwide every year.

Applications of mice in user interfaces

Usually, the mouse is used to control the motion of a cursor in two dimensions in a graphical user interface. Objects, such as files, programs, or actions, can be selected from a list of names, but, alternatively, are often represented visually by pictures called icons and buttons; the mouse cursor can be used to select or activate items by moving the cursor over the name or picture and pressing one of the mouse buttons. For example, a text file might be represented by a picture of a piece of notebook paper, and clicking on this icon might cause a text editing program to open the file in a new window. (See also point-and-click.)

Mice can also be used gesturally — that is, a stylized motion of the mouse cursor itself can be used as a form of input. In a gestural interface, a particular "gesture" (stylized motion) may be mapped to an action: for example, in a drawing program, moving the mouse in a rapid "x" motion over a shape might delete the shape.

Gestural interfaces are rarer, and often harder to use, than plain pointing and clicking, because they require more fine motor control of the user. However, a few gestural conventions have become widespread, including the drag-and-drop gesture, in which:

  • the user presses the mouse button while the mouse cursor is over an object,
  • then holds down the button while moving the cursor to a different location,
  • and finally releases the mouse button.

This motion is commonly used to move the item from one location to another — the item is "dragged" from its old location and "dropped" in its new one. For example, a user might drag and drop a picture of a file from a folder onto a picture of a trash can, indicating that the file should be deleted.

Other uses of the mouse's input are common in special application domains. In interactive three-dimensional graphics, the mouse's motion is often directly translated into changes in the virtual camera's orientation. For example, in the Quake computer game, the mouse is usually used to control the direction in which the player's "head" faces: moving the mouse up will cause the player to look up, revealing the view above the player's head.

When mice have more than one button, software may assign different functions to each button. Often, the leftmost button on the mouse will select items, and the rightmost button will bring up a menu of alternative actions applicable to that item. For example, on platforms with more than one button, the Mozilla web browser will follow a link in response to a left button click, will bring up a menu of alternative actions for that link in response to a right button click, and will often open the link in a new tab or window in response to a click with the middle mouse button.

One, two or three mouse buttons?

The issue of whether a mouse should have exactly one button or more than one has attracted a surprising amount of controversy. From the first Macintosh onward, Apple always shipped computers with a single-button mouse, whereas most other platforms used a multi-button mouse. Apple and its advocates claim that single-button mice are more efficient, and that multi-button mice are confusing for novice users. The Macintosh user interface was designed so that all functions were available with a single button mouse. Apple's Human Interface Guidelines still specify that all functions need be available with a single button mouse. Unfortunately, X11 applications, which Mac OS X can also run, were designed with the use of 2 or even 3 button mice in mind, causing even simple operations like "cut and paste" to become awkward. Mac OS X natively supports multi-button mice, so many users do choose to use third-party mice on their Macintoshes.

Advocates of multiple-button mice point out that the lack of additional mouse buttons often leads to clumsy workarounds in interfaces where more than one action may be useful for a given object. For example, in the Macintosh Finder, the user single-clicked to select a file, and double-clicked in order to open that file. Usability studies have found that the double-click is confusing and hard to use — for example, users with poor motor skills may not perform the second click fast enough, so that the action is interpreted as two single clicks rather than a double click. However, virtually all modern interfaces require the user to double-click even if he or she has a two-button mouse, eliminating any advantage, if the option for general conversion to single-click mode is not enabled. The speed of the double click is usually configurable, and most multiple-button mice can be set to put out two clicks when one button is pressed.

Furthermore, "press-and-hold" techniques are a common workaround on systems with one-button mice. In a press-and-hold, the user presses and holds the single button, and after a certain period, the button press is not perceived as a single click but as a separate action. On Macintosh platforms, Netscape used press-and-hold to substitute for a second mouse button. This has two drawbacks: first, as with double-clicking, a slow user may press-and-hold inadvertently. Second, the user must wait while the software detects that the click is actually a press-and-hold, or their press might be interpreted as a single click. Furthermore, the remedies for these two drawbacks conflict with each other: the longer the lag time, the more the user must wait; and the shorter the lag time, the more likely it is that some user will accidentally press-and-hold when meaning to click.

Finally, the user may be required to hold down a key on the keyboard while pressing the button (otherwise known as mouse chording). This has the disadvantage that it requires that both the user's hands be engaged. It also requires that the user do two actions on completely separate devices in concert, that is, pressing a key on the keyboard while pressing a button on the mouse. Studies have found all of the above less usable than additional mouse buttons for experienced users. Today, many widely used Macintosh software packages, including web browsers and graphics editing programs, use one or more of the above workarounds. Critics of single-button mice point to these facts as evidence that mice should have more than one button.

Most Unix machines or systems running variations of Unix like Linux or FreeBSD run The X Window System which almost always requires a three button mouse. In The X Window System the buttons are numbered by convention. This allows user instructions to apply to mice or pointing devices that do not use conventional button placement. For example a left handed user may reverse the buttons, usually with a software setting. With non-conventional button placement user directions that say "left mouse button" or "right mouse button" are confusing. The ground-breaking Xerox Parc Alto and Dorado computers from the mid-1970s used three-button mice and each button was assigned a color. Red was used for the left (or primary) button, yellow for the middle (secondary) and blue for the right (meta or tertiary). This naming-convention lives on in some SmallTalk environments such as Squeak and can be less confusing than the right, middle and left designations.

Newer mice have a scroll wheel between two buttons with the scroll wheel acting as a middle mouse button (button two).


Mice are often used as an interface for computer games, and sometimes for video games. They are often used in combination with keyboards.


A mouse is a favorite way to play fps games. The X axis of the mouse is used for looking left and right, while the Y axis is used for looking up and down. The left mouse button is usually for primary fire. The right button is used for secondary fire of the selected gun. Scroll wheel is used for changing weapons. On most fps games, these buttons assignments. Functions may also be assigned to thumb buttons. A keyboard is usually used for movement and other functions.


Many strategy games are played using a mouse, and usually use a cursor for control.

See also

External links

  • Optical Mice and how they Work
  • Optical Mouse technology review: Tech specs on current optical mice


  • Agilent Technologies (2004). ADNS-2610 Optical Mouse Sensor . Retrieved 2004-11-16 .
  • Squeak Wiki (16 March, 2004). FAQ: Mouse Buttons . Revision 24. Retrieved 2004-11-17 .

Last updated: 02-11-2005 01:31:43
Last updated: 05-06-2005 01:27:49