Fasd (pronounced similar to "fast") is a command-line productivity booster. Fasd offers quick access to files and directories for POSIX shells. It is inspired by tools like autojump, z and v. Fasd keeps track of files and directories you have accessed, so that you can quickly reference them in the command line.
The name fasd comes from the default suggested aliases f(files), a(files/directories), s(show/search/select), d(directories).
Fasd ranks files and directories by "frecency," that is, by both "frequency" and "recency." The term "frecency" was first coined by Mozilla and used in Firefox (link).