A tanner is a worker who changes animal skins into leather. In New Testament times, tanners soaked animal skins in lime and plant materials to make leather (this process is called tanning). Because this process created strong, bad smells, tanners had to live and work outside of towns.
The coverings for the tabernacle (the holy tent) were made from tanned ram and goat skins, or possibly sea cow skins. These leather coverings were red, either because they were dyed or because of how they were tanned (Exodus 25:5; 26:14; 35:7, 23; 36:19; 39:34).
The Bible mentions only one tanner by name, Simon. He lived in Joppa. The apostle Peter stayed at Simon's house (Acts 9:43; 10:6, 32).