Sum-of-Products Form

Sum-of-Products Form is a standard way of writing a Boolean Function, where terms built with the AND operator (products) are combined with the OR operator (sum).

For example: $f(x, y, z) = xy + xz + yz$

Every Boolean function can be written in this form. To build it from a truth table, take each row where the function equals 1, write a product term where inputs equal to 1 appear uncomplemented and inputs equal to 0 appear complemented, then OR all of those terms together. The result isn't necessarily the simplest expression, so it's often simplified afterwards with Boolean Algebra theorems or a Karnaugh Map.

The dual form is the Product-of-Sums Form. See Week 9 - Boolean Algebra A.