Authentication it’s a huge component on your app, it will enable to build a relation with your users.
Sign up or Registration, Sign in or Log in, you name it, these are the key to engage with them. Whether you want users to participate by leaving comments, blogging, leaving messages onto boards, posting photos or creating a personal network - participation needs to be attributed and/or associated with the user for purposes of building community and reputation, or creating a personal profile or knowledge base. This is why is imperative to build authentication the right way!