Software

Software is a set of computer programs "Computer program") and associated documentation and data. This is in contrast to hardware "Computer hardware"), from which the system is built and which actually performs the work.

At the lowest programming level, executable code consists of machine language instructions supported by an individual processor "Microprocessor")—typically a central processing unit "Central processing unit") (CPU) or a graphics processing unit  (GPU). Machine language consists of groups of binary values "Binary number") signifying processor instructions "Instruction set architecture") that change the state of the computer from its preceding state. For example, an instruction may change the value stored in a particular storage location in the computer—an effect that is not directly observable to the user. An instruction may also invoke "System call") one of many input or output operations "Input/output"), for example displaying some text on a computer screen; causing state changes which should be visible to the user "User (computing)"). The processor executes the instructions in the order they are provided, unless it is instructed to "jump" to a different instruction, or is interrupted by the operating system. As of 2015, most personal computers "Personal computer"), smartphone devices and servers have processors with multiple execution units  or multiple processors performing computation together, and computing has become a much more concurrent activity than in the past.