A type of mathematics in which letters (called "variables") stand in for numerical values and can be manipulated according to the laws of arithmetic. Algebra is used in mathematics (and computer programming) to describe general relational statements of values to each other. A very basic algebraic expression is:
'x + 1 = 5'
where x would, in this case, equal 4, or perhaps to another algebraic expression. One particular branch of algebra relevant to computing is known as Boolean algebra, which deals with logical rather than numerical relations between sets of values.
Algebra itself was developed around the Ninth Century by Persian mathematician Al-Kwarizmi, but didn't make its way into Europe until several hundred years later, when the Arab city of Toledo (in Spain) was sacked. Arabic knowledge (much of it mathematical) then spread throughout Europe. The word algebra derives from the Arabic al-Jabr, which some sources claim was a mathematician. The word jabara,. however, means, in Arabic, "to set or consolidate."