Canals are man-made waterways, usually connecting existing lakes, rivers, or oceans. They are used for transportation, often by barges or narrowboats on smaller canals, and by ships on ship canals that connect to the ocean. Inland canals preceded the development of railroads during the Industrial Revolution, and some canals were later drained and used as railroad right-of-way.

Irrigation canals are man-made waterways for the delivery of water and preceded the use of transportation canals.

Canals have found another use in the 21st century, as wayleaves for fibre optic telecommunications networks.

See also:

• Canal lock
• Horse-drawn boat
• Ship canal
• Sluice
• List of waterways,
• List of canals in the United States,
• List of rivers in the United States,
• Canals of the United Kingdom,
• Rivers of the United Kingdom,
• Waterway restoration
• Suez Canal
• Panama Canal
• Venice
• Amsterdam

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For a time until the early 20th century, it was believed that there were canals on Mars

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Canals is a commune in the Tarn-et-Garonne département in France.