Yogi,A linear equation is an equation which graphs to form a line.It usually takes the form of y = ax+b where a and b are constants such as y=2x+1.When you graph it, it forms a strait line, so they call it a linear equation.Here is a video that might help you understand more:http://www.khanacademy.org/math/algebra/linear-equations-and-inequalitie/graphing_solutions2/v/algebra--graphing-lines-1