Streams are an abstraction to interact with these in a uniform way. This library uses what are called streams to operate with physical devices such as keyboards, printers, terminals or with any other type of files supported by the system. The vast majority of modern operating systems have inherited streams from Unix, and many languages in the C programming language family have inherited C's file I/O interface with few if any changes (for example, PHP). The stream model of file I/O was popularized by Unix, which was developed concurrently with the C programming language itself. Unlike some earlier programming languages, C has no direct support for random-access data files to read from a record in the middle of a file, the programmer must create a stream, seek to the middle of the file, and then read bytes in sequence from the stream.
The I/O functionality of C is fairly low-level by modern standards C abstracts all file operations into operations on streams of bytes, which may be 'input streams' or 'output streams'. The functionality descends from a 'portable I/O package' written by Mike Lesk at Bell Labs in the early 1970s, and officially became part of the Unix operating system in Version 7. These functions make up the bulk of the C standard library header. The C programming language provides many standard library functions for file input and output.
