A1 is popularly used to indicate the highest degree of excellence. Other possible meanings include:

A1 (band), a British boy band.

A1 (code), used in computer programming.

A1 (milk) , milk containing a particular protein supposed by some to cause heart disease.

A1 (primary auditory cortex), the part of the brain processing hearing.

A1 (sauce) , a steak sauce .

A1 (shipping), used to indicating shipbuilding quality.

A1 (rocket)

A1 is an ISO 216 paper size.

There are also several roads and freeways named the A1:

A1 freeway (Austria)

A1 road (Britain) from London to Edinburgh

A1 freeway (Cyprus)

A1 freeway (France) from Paris the Belgian border

A1 freeway (Germany)

A1 road (Italy) from Milan to Naples

A1 highway (Lithuania) from Vilnius to Klaipėda

A1 road (Northern Ireland) from Belfast to Newry

A1 freeway (Poland)

A1 freeway (Romania)

A1 freeway (Spain)

A1 (Switzerland)

The A1 Ring is the name of a race track in Austria which formerly hosted a round of the Formula One championship.