Expansion may refer to:

• In physics:

*expansion of space,

*thermal expansion,

*expansion fan.

• In computer hardware: an expansion card
• In computer programming: JEE5 developing tool in-line expansion
• In engineering expansion is the increase in the size of a material and or other products such as the expansion of plastic or metal. By Matthew Barber
• In computer gaming:

*an expansion pack

*(in real time strategy games like Starcraft) building a secondary base to gather more resources.

• In mathematics:

*polynomial expansion

*Taylor Expansion

*expansion of a graph

*the converse of a reduct, in model theory or universal algebra.

• An expansion team in sports.
• In medicine, a trinucleotide repeat expansion disorder is the result of expansion during DNA translation.
• An album by Dave Burrell.

• In economics: economic expansion
• In audio engineering: audio level expansion (or squelch)