Does concrete always crack?

It will always crack,

but the way it cracks and the width of the crack can be manipulated by rebar and the concrete mixture so the crack will not harm the concrete or rebar

Every concrete driveway, concrete patio, concrete sidewalk, etc., will crack sooner or later. This doesn’t mean it’s going to happen in the near future. When concrete is properly placed, and aggressive precautions are taken, it can literally take30 years before it cracks.

Yes.

It will eventually get very hard.

It will eventually crack.

depending on

Design stage for example not allowed to concrete crack for element touch water like tank  so we use non crack stage for concrete this for Design

for site or construction depending on curing for concrete and degree for concrete and ........elect   and most time crack in site