Affiliate system allow affiliates to earn a profit through purchases/subscription made by their clients. It encourages your members to share and introduce your website to others. It is a perfect tool to track referrals to your website.
It is an essential plugin that is similar to the popular (UrbanDictionary) which allow you to create a community-driven dictionary. Your members can post definition to words and phrases. Definitions are Upvoted or Downvoted and it can contain GIF Image which allow your platform to be more Fun, Engaging and also Educative.