Due to the risks of illegal, inappropriate, and abusive website, hosts with instant activation usually give very little storage space and monthly bandwidth. Other restrictions will likely also be in effect. The webhosts usually either require the users' web pages to display their banner ads, textlink ads, or popups; or else the users' files to be uploaded through a web-based file manager that display ads to the user uploading files.
Hosts with instant activation are often abused, such as link spamming.
Post for Hosting
Some free hosts require posting in a forum. Forum-based free hosting requires users to either reach a certain amount of posts before getting a free hosting account, or be an active contributor in the forum. Forum-based free hosting often work on a system of points where posts give points to a user and can be used as credits toward getting a hosting account or more resources. Typically, the forum where users have to post contains advertising as the hosts way of making a profit.
This method is popular, as the hosts can decide which applications to deny and allow. This is common when a popular forum has free hosting as an add-on service, rather than the other way around.