A series is a related set of things that occur one after the other (in a succession) or are otherwise connected one after the other (in a sequence). The specific meaning depends on the context.

In science:

• series (mathematics), the sum of a sequence of terms
• series (botany), named selections of plants and flowers in botany
• series circuit, a way of connecting electrical circuits (see series and parallel circuits#Series circuits)
• seriation, a method of dating objects in archaeology