Athlon is a name for AMD’s main line of Intel-compatible CPUs.
The Athlon line is designed to complete against the Intel Pentium CPUs.
Athlon CPUs feature a L1 cache with 64KB of memory for data and another 64KB of memory for instructions.
Athlon CPUs support MMX, 3DNow!, and SSE. Some models of Athlon CPUs also support SSE2.
Athlon CPUs are slowly being phased out in favor of the newer Athlon 64 family of CPUs.