What is Jainism and how is it linked to Buddhism?

Another sect of people related to Hinduism just like Buddhism.It was founded by lord Mahavira a few years later than Buddhism.Jains follow some specific rules which are very strict as compared to Hinduism and Buddhism.They're strictly vegetarian and don't eat anything that grows beneath the earth like onions,carrots,raddish etc.They constantly keep their mouth covered by cloth to avoid any small micro organisms entering the mouth I guess.These 're a few things I heard regarding Jain people.