Penetration may refer to any of the following:
1. In telecommunications, penetration can mean the act of trying to circumvent or break through a security barrier, like a firewall or encryption. A penetration tester (pentester) uses any methods at their disposal to identify and exploit vulnerabilities in the target system.
To help prevent penetrations, companies may conduct or hire outside companies to conduct penetration tests to help make sure their networks and computers are secure.
2. Penetration can also mean the physical act of penetrating a solid wall, for the purpose of running wire or cable through it. Similarly, a radio signal is said to be in the act of penetration when it passes through a solid wall.