In a wood working, we need to understand Stain and Finish.
Stain, give the wood a nice surface looking oil stain. It will change wood colour, do not have enough protection with the lumber or board. We usually use stain to give the wood a rice and great colour on surface. Beside, we can use different colour in opposite sides with designing.
Finish, build a protection level on the surface. We have many different choices in this kind, such as, Polyurethane, Oil-Based, Water-Based, Lacquer, Varnish and Shellac. Choose the right finish on different project. https://www.tabtu.top/?p=897