Sends and inserts
An insert processes the whole signal in the channel path. A send taps off a copy, so the dry sound stays and several tracks can share one reverb or delay.
An insert sits in the channel path. The whole signal goes through it, and what comes out replaces what went in. The EQ and compressor on a channel are inserts. A group or the master can add another through the Stagebox.
A send taps off a copy. The channel keeps its dry signal, and the send level decides how much of it feeds a shared effect. Every mixer channel has built-in reverb and delay sends, plus any custom sends patched on the Stagebox. One reverb, a send level per channel: the vocal can sit further back than the kit without two rooms. The controls are on FX Sends.
Put EQ, compression, and filters in the path when you want the processed sound to be the sound. Use a send when several tracks should share one space. Mixing a heavily processed copy back under the original is parallel processing.