A stellar-mass black hole (aka stellar black hole or stellar remnant black hole) is a black hole that is a stellar remnant, the remains of a star. They fall within the mass-range of stars, on the order of 5-50 solar masses. They result from stars of considerable mass (less massive stars either just cool, become white dwarves or neutron stars), but they should have lost considerable mass before becoming black holes, from strong stellar wind as post-main-sequence stars and the possible core collapse supernova. The mass range is bounded by mass gaps, i.e., mass ranges in which no black holes are found or should be found. The lower mass gap (less than 5 solar masses) is observed but with as yet no consensus explanation. The upper mass gap stems from theory, but a few apparent exceptions have been observed and need explanation.
Identification of stellar-mass black holes is not quite certain, so discoveries are often classified as black hole candidates for considerable time, and some might consider all of them to be in that category. Detection is either from interaction with a binary-star companion (e.g., X-rays from accretion, a microquasar), or orbits (or other kinematics) indicating an unobserved massive object that should be observed if it is not a black hole, or through a GW detection (extra-galactic). Some tens of candidates are known within the Milky Way.