Like terms are two or more terms in an algebraic expression that have the same variable with the same exponent. $$\begin{array}{c}7xy+2x-3xy-2x^2+x+5x^2\end{array}$$ In this expression, there are three sets of like terms: $xy\text{-terms},$ $x\text{-terms},$ and $x^2\text{-terms}.$

Note that all constants are like terms, and can thus be combined.