VHS looks like one simple format, but there is a small tangle of speeds, standards, and variants hiding inside it. Here is the whole family tree, kept as painless as we can manage.
A blank VHS tape can record at three different speeds, and the speed you choose trades quality against how much you can fit on the tape.
The rule of thumb: faster speed equals better picture but less runtime. If a home-recorded tape looks unusually soft, it was probably taped in EP to squeeze more on.
The world could not agree on one broadcast standard, so tapes come in three flavours. NTSC was used mainly in North America and Japan, PAL across most of Europe and Australia, and SECAM in France and parts of Eastern Europe and beyond. A tape recorded in one standard will not play properly on a machine built for another (you get no picture, no colour, or a rolling mess). This is why that bargain tape you ordered from overseas plays as gibberish: it is not broken, it is just foreign. A multi-system VCR is the cure.
Super VHS, a higher-quality version of the format with noticeably sharper picture. It needs an S-VHS deck to get the full benefit, though those decks happily play standard tapes as well. A genuinely nice upgrade if you find one.
VHS-C ('C' for compact) was the small cassette used in camcorders so people could film weddings and birthdays without lugging a full-size deck on their shoulder. The tape inside is the same VHS tape, just in a smaller shell. To play one in a normal VCR, you slot it into a full-size VHS-C adapter, which is a cassette-shaped shell that fits the little tape and lets a standard machine read it. If you have inherited a box of home movies, check whether they are these little ones, because you will need the adapter.
And we cannot leave without a respectful word for Betamax, the rival format that was arguably better and lost anyway, because being better has never once been enough. It is not compatible with VHS in any way, needs its own machines, and limped on until 2016. If your dusty tapes turn out to be Beta, you have our sympathies and our respect. Pour one out.