$q,$ is a subset of e$-$commerce that involves clectronic transactions between consumers using a thind phity to facilitate the process.

Business$-$to$-$business $($B$2$B$)$ e$-$commerce

Consumer$-$to$-$consumer $($C$2$C$)$ e$-$commerce

Business$-$to$-$consumer $($B$2$C$)$ e$-$commerce

Consumer$-$to$-$business $($C$2$B$)$ e$-$commerce