# Is there a set of NP-hard problems that are most commonly used for proving NP-hardness?

Are there any NP-hard problems that are considered kind of the standard for reductions? There's so many but it feels like some come up more often than others (for example Vertex Cover, Independent Set, 3-SAT, etc.). I'm sure people just pick whatever is most convenient, but where's the boundary between "more useful" and "too obscure" when choosing a problem to reduce from?