In computing, a code segment, also known as a text segment or simply as text, is one of the sections of a program in an object file or in memory, which contains executable instructions.
It has a fixed size and is usually read-only. If the text section is not read-only, then the particular architecture allows self-modifying code. Fixed-position or position independent code may be shared in memory by several processes in segmented or paged memory systems.
As a memory region, a code segment may be placed below the heap or stack in order to prevent heap and stack overflows from overwriting it.