Capturing will take packets from a network adapter, and save them to a file on your harddisk.

To hide all the lowlevel machine dependent details from Wireshark, the libpcap/WinPcap (see Section 5.9, “libpcap/WinPcap (optional)”) library is used. This library provides a general purpose interface to capture packets from a lot of different network interface types (Ethernet, Token Ring, ...).