Assuming we're in the UK, the main standards are:-
Fixed wing under 450 kg (microlight / Small Light Aeroplanes) BCAR Section S (Just gone to issue 2, issue 1 only went up to 390kg)
Fixed Wing under 750 kg (Very Light Aeroplanes) - JAR-VLA
Gliders and Fixed Wing Motorgliders under 850 kg (SLMG), JAR-22
Utility, aerobatic and commuter aircraft - JAR-23 (This has replaced the older BCAR Section K, which in many ways is more useful and you can still get for reference)
Airliners - JAR-25
JAR-23 and FAR-23 are for all reasonably purposes identical, as are JAR/FAR-25. The others are primarily Europe / UK only standards. That said Section S and JAR-VLA are gaining popularity in other English speaking countries.
All can be mail ordered from a company called Westward Digital (aka CAA printing services) on 01242-235151. BCARs are about £8, JARs are around £30-£50 each.
Hope this helps,
G