In computer science, source code (commonly just source or code) is any sequence of statements and/or declarations written in some human-readable computer programming language. The source code which constitutes a program is usually held in one or more text files, sometimes stored in databases as stored procedures and may also appear as code snippets printed in books or other media. A large collection of source code files may be organized into a directory tree, in which case it may also be known as a source tree. A computer program's source code is the collection of files needed to convert from human-readable form to some kind of computer-executable form. The source code may be converted into an executable file by a compiler, or executed on the fly from the human readable form with the aid of an interpreter. The code base of a programming project is the larger collection of all the source code of all the computer programs which make up the project.