Wireshark is the world's foremost network protocol analyzer. It lets you see what's happening on your network at a microscopic level. It is used across many industries and educational institutions.It is a network packet analyzer. A network packet analyzer will try to capture network packets and tries to display that packet data as detailed as possible.You could think of a network packet analyzer as a measuring device used to examine what's going on inside a network cable, just like a voltmeter is used by an electrician to examine what's going on inside an electric cable.
However, with the advent of Wireshark, all that has changed. Wireshark is perhaps one of the best open source packet analyzers available today.