sandbox
a sealed space for running untrusted code
A sandbox is an isolated environment where code runs without reaching the rest of a system. It is used to test programs, run outsiders' code or evaluate AI agents safely. Its safety depends on every allowed exit being secure. A sandbox that can be escaped, or that runs anyone's code publicly, becomes a launchpad for attacks.
Think of it as
A sandpit with walls: play freely inside, but nothing should get out.