Shellac
Shellac is a resin dissolved in alcohol, harvested in India, and the most repairable finish in the trade. A shellac finish can be patched with a fresh coat; the lines disappear. The downside is that it is water-marked and alcohol-marked, and the finish dissolves if you spill bourbon on it. Use it for drawer interiors, casework backs, French-polished topcoats, and any surface that needs to be repaired without refinishing. A 1-pound cut is the default; a 2-pound cut is a sealer; a 3-pound cut is a build coat. Wax over it for a soft sheen.
Wax
Wax is a paste (carnauba, beeswax, paraffin) buffed onto a surface. The oldest finish, the most forgiving, the easiest to repair, and the softest. A wax finish will look beautiful on a dresser and will not survive a wet glass. For a working surface, wax over shellac, wax over oil, or wax over a cured film finish. Wax alone is a finishing-room choice, not a kitchen-table choice.
Oil
Boiled linseed oil, tung oil, walnut oil, mineral oil, and the modern blends (Waterlox, Tru-Oil, Osmo) are penetrating finishes that cure inside the wood. The easiest to apply, the easiest to repair, and food-safe when cured. Mineral oil is the default for cutting boards, spoons, and anything that touches food. Flood it on, wipe it off, wait 24 hours, repeat. Six coats is the working minimum. Sand lightly between coats with 0000 steel wool.
What to use when
The honest rule: a regional handyman business should own a quart of shellac, a tin of paste wax, a pint of boiled linseed oil, and a quart of mineral oil. That is the entire kit. Everything else is a varnish, a poly, or a product intended for a furniture showroom.