How to allow user to use my app?

Should an app request a login before allowing users to use it? Why?

• I'm working on this social network web app. The app allows interactions amongst users, and people can post stuff both to their following and to non-followers. The initial idea was to allow users to use the app, and then request for them to login when there is the need for them to use social features such as commenting, etc. Upon second thought however I think like any standard network, users should be asked to login into the app first, before using the site. Otherwise they can select: "browse site as guest". I think the main advantage with this is user acuqisition. Which is the best UX Practice?

• Answer:

  yes I think it should that way you can keep tabs on how many people are using the app itself.