Reusable period products fall into three main categories:

• Cloth Sanitary Pads (CSP) – a washable alternative to disposable sanitary pads.
• Period underwear – knickers/pants available in as many styles as regular underwear. They have built in absorbency but are so slim you’d never notice. Just wear as normal and then wash. You can also get period swimwear.
• Cups – broadly speaking a replacement for tampons but they can hold far more and many people are able to use them for far longer stretches of time. You can also get discs which are essentially the same thing but a different shape.

There are also environmentally-friendly versions of the plastic-based single use period products. These are normally made from natural materials (such as wood-pulp) rather than plastic.

I have linked the reviews I have done of eco period products from this page.