Stain shows everything in a slab. Patches, old glue, the line where a wall used to sit. It's like painting an old tractor, where every dent shows once the color's on. So before we start, I walk the floor with you and point out where the color may come out different, so nothing about the finished floor surprises you.
Then we choose acid or water-based stain by the look you're after. If the color you want is an earth tone, I'd lean toward acid stain, because nothing else gives that mottled depth. Most of the floor failures I've seen started under the finish, so we take our time on cleaning and grinding before any color goes down.
Stain also suits many basement slabs, and if yours shows moisture, we sort that out first as part of planning your basement flooring. If you want stone or glass chips set into a polished pattern, that's terrazzo flooring, a different job I'm glad to walk you through.