Software

Software is a collection
of instructions that tell a computer how to work. This
is in contrast to 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—typically
a central processing
unit (CPU) or a graphics
processing unit (GPU). A machine language consists of groups
of binary values signifying processor
instructions 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 one of many input or output operations, for example
displaying some text on a computer screen; causing state changes that should
be visible to the user. 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, 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.