Foley Sound was named after Jack Foley, who was a sound designer at universal studios. It is the process in which a sound recordist will create sounds that are diegetic within the film. These are sounds that relate to the movements of actors and sound effects that are visible as actions within the film. These differ from sound effects though. For example, cars and gunshots are sound effects but not foley. Foley ranges from footsteps to clothes rustling sounds.
The foley team usually consists of a ‘walker’ who is the creator of the foley sound, and then the recordist/ engineer who records these sounds in to the DAW (Namely pro Tools). This would take place inside a sound theatre or foley stage. Using a range of microphones to record these sounds, the engineer would talk back through a talkback mic, to communicate with the walker (foley creator). They would give instructions (Ie watch the screen and imitate the sound using these devices).
The foley stage (or studio) usually contains a plethora of unwanted items, or ‘junk’. These studios can hold all sorts of items, such as shoes, high heels, bottles, flasks, clocks, surfaces for walking on to create the footsteps, and much more.
Sound artists that are known as ‘Audiles’ are the most successful in foley production because they can think outside the box when it comes to the creation of the sounds.
Foley adds a certain ‘aural depth’ to the film. Without it, the actors would be talking in what would seem like an empty space, compared to as a vacuum. It brings about a realism that cannot fully be achieved with dialogue recording microphones. For example it brings the audio straight the front of the mix, instead of being in the shots from the start. The sound recordist has much more control over this because they can mix down and change each and every individual sound that is present in the foley mix.
http://filmsound.org/terminology/foley.htm
https://www.sound-ideas.com/Page/what-is-foley.aspx