Other forms: closed systems
A closed system is any system that doesn't release or take in matter but does exchange energy. A lidded water bottle in the sun is a closed system because no water gets out, but it does become warmer.
In computer technology, a closed system is self-contained, proprietary, and often controlled by a single developer or manufacturer. The hardware and software are designed to work easily together, but users can't integrate programs from unapproved, outside systems. When it comes to physics and chemistry, closed systems exchange energy with the world around them, but no physical material enters or exits. An unopened soda can is a closed system — no liquid or gas can escape, but heat energy can easily pass through the metal to warm it up or cool it off.