The Canonical Csound Manual provides the authoritative Reference for each opcode and the various Csound Options (command line flags).

On each opcode page one or more examples for a basic or advanced usage are provided. Overview pages offer help to find opcodes or GEN routines.

Note that the Reference Manual is not meant as introduction to Csound. For this purpose, have a look at the FLOSS Manual or at the Get Started on this site.