A series is the result of adding together the terms of a sequence. While a sequence is a list of numbers or terms in a specific order, a series is the sum of these terms. A series is typically written using the summation symbol as shown below.

Series can be finite or infinite. A critical concept associated with infinite series is convergence. An infinite series converges if the sum approaches a finite value as the number of terms increases indefinitely. Conversely, if the sum does not approach a finite value, the series diverges.