A toilet leaking at the base most often has a failed wax ring, the seal between the toilet and the floor flange. Loose closet bolts, a cracked flange, a cracked bowl, condensation, or a drip from the supply line or tank bolts can leave the same puddle, so the first job is finding where the water starts.
The wax ring causes most base leaks because it only seals while the toilet sits still. If the toilet rocks, even slightly, water escapes with each flush. Loose bolts let it rock, and a cracked or corroded flange cannot hold the bolts tight. On a slab, soil movement can shift the flange enough to break the seal. Wax rings are single use, so the fix is resetting the toilet on a new ring, as the toilet repair page explains.
A simple test tells the causes apart. Dry the toilet and floor, then wait without flushing. If water returns while nobody uses it, look higher: beads on the tank in humid weather mean condensation, and a wet supply line, shutoff valve or tank bolt means a drip running down to the floor. Add a few drops of food coloring to the tank; colored drips on the outside point to the tank bolts or gasket. Then flush. Water seeping from under the base during or right after a flush points to the wax ring or flange.
One honest limit: the test finds the source, not the damage already done. Each flush pushes water under the toilet into the subfloor, so a soft spot around the base or a stain on the ceiling below can mean the floor needs repair before the toilet is reset. Caulking around the base does not stop a failed seal; it only hides the leak.