Yin Yoga is well-known for its very peaceful slow, passive and restorative asanas holded for 3-5 minutes to reach our deeper layers of some muscles and connective tissues.
For me personally yin yoga was a first step into yoga. I did a lot of sports and forgot about stretching at all. Yin is super helpful with that and except perfect physical benefits it has ability to calm your mind, bring you peace and happiness.
It's better if you have a blanket, cushion and block. Sometimes for myself I use a belt as well. But it's not necessary.