Many knows these terms because have heard them, many others know them very well and many others mone really doesn’t know what they mean. So tas the mobile wolrd as become a big trend and many people follow the news about i tought is useful to give their definitions:
unlocking: it’s the procedure that allows to use any SIM on mobile device so isn’t limited to just one carrer
jailbreaking: term used for Apple devices, it means to unlock them related to permissions for the goal to have a full control (install any app etc…), to make a comparison is like to have administrations rights on Windows
rooting is the same concept of jailbreaking but related to Android OS devices. In this case is called rooting because Android is an open source Linux based OS, and as many knows administrator user under Linux is root
tethering is the use of a mobile device such as a mobile phone to supply Internet access for another device which is otherwise unconnected, using the mobile device as a modem