Your estimate says wire mesh or rebar
It shows up as one line on the paperwork, and it is easy to skim past as a detail that does not matter much. It is a real choice, and it changes what the slab can carry and how it behaves years down the road if the ground under it ever moves.
Neither option is a way to save money at the other's expense. Both are legitimate, and which one belongs on your job comes down to what the slab is going to sit on and what is going to sit on the slab.
What each one actually is
Wire mesh is a welded grid of steel wire, shipped flat or in rolls, laid across the base before the pour. Rebar is solid steel bar, tied by hand into a grid at the spacing the job calls for, and held up off the ground on chairs so it sits in the middle of the slab instead of on the dirt underneath it.
- Wire mesh: welded grid, common on standard flatwork
- Rebar: tied bar on chairs, the upgrade for load and movement
Placement matters as much as the material
Either one only works if it ends up inside the concrete, not underneath it. Mesh left flat on the stone base does almost nothing; it has to be pulled up into the slab as the pour comes across it. Rebar gets set on chairs before the pour starts, for the same reason. Steel sitting at the bottom of a form is steel that is not doing its job.
It is one of the easiest details to get wrong and one of the hardest to check once the concrete is down, which is exactly why it matters who is holding the rake when the load comes across the wire.
Where mesh is the right call
A standard driveway, patio or walkway carrying a car, a pickup and normal foot traffic is squarely mesh territory, and it has been doing that job on flatwork for a long time. It is not a lesser choice for that use, it is the right one.
Where rebar earns its keep
Anything carrying heavier loads, a dump truck, a loaded trailer, a piece of equipment, benefits from rebar's added strength across a soft spot in the base. So does a slab poured on fill, on a slope, or long enough to flex over its length. Rebar also does something mesh does not: if a crack ever opens, it holds the two sides together instead of letting them move apart.
Footings and foundation walls are not a judgment call either way. Steel there carries real tension in the concrete, run continuous and lapped at the splices, with the corners tied on bent bar so the steel turns the corner instead of stopping at it. It is standard on every foundation job we pour.