The standard form of a linear equation is
Ax + By = C.
The disadvantage is that A, B, and C do not stand for anything obvious (like the slope or y-intercept). In fact, they are not unique: if we double them all, we get back the same line! You can check this with the following example.
x + 2y = 3
2x + 4y = 6
These two equations, both in standard form, represent the same line.