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

In entertainment:

• television series, a periodically returning television program or a single year (season) of episodes. An animated series is produced by means of animation
• film series, a group of films that (usually) have the same director, cast, and a consistent story line
• book series, a group of novels that may share a common setting, story, set of characters or timeline
• serialism, a rigorous system of writing music
• video game series, a number of games, often including recurring characters (see List of video game franchises)

In sports:

• In sports and games, a sequence of competitive events between two teams or individual competitors – perhaps to decide a championship – is often called a series. See: playoff format

In nomenclature

• 2 in a series = Sequel or Duology
• 3 in a series = Trilogy or Triptych
• 4 in a series = Tetralogy
• 5 in a series = Pentalogy
• 6 in a series = hexology
• 7 in a series = heptalogy
• 8 in a series = octology
• 9 in a series = nonology
• 10 in a series = decology
• 11 in a series = undecology
• 12 in a series = dudecology

Other uses:

• On U.S. currency, series refers to the year appearing on the front of a bill, indicating when the bill's design was adopted.

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