To decompile is to convert executable (ready-to-run) program code (sometimes called object code ) into some form of higher-level programming language so that it can be read by a human. Decompilation is a type of reverse engineering that does the opposite of what a compiler does. The tool that accomplishes this is called a decompiler. A similar tool, called a disassembler, translates object code into assembler language. There are a number of different reasons for decompilation or disassembly, such as understanding a program, recovering the source code for purposes of archiving or updating, finding virus es, debugging programs, and translating obsolete code. Decompilation was first used in the 1960s to facilitate the migration of a program from one platform to another.
Decompilation is not always successful for a number of reasons. It is not possible to decompile all programs, and data and code are difficult to separate, because both are represented similarly in most current computer systems. The meaningful names that programmers give variable s and function s (to make them more easily identifiable) are not usually stored in an executable file, so they are not usually recovered in decompiling.
Decompilation is sometimes used unethically, to reproduce source code for reuse or adaptation without permission of the copyright holder. Programs can be designed to be resistant to decompilation through protective means such as obfuscation .