The release of JSR 286: Portlet Specification 2.0, in June 2008, cemented Portlet technology as one of the most popular web development technologies currently available. Over 20 popular open source Portlet containers and portals are currently available; including the Sun Liferay portal, the eXo Platform, Jakarta Pluto, etc. In addition, there are numerous offerings from major software vendors, such as Vignette Portal, IBM WebSphere Portal, Sun OpenPortal, Oracle Portal, and so on.

A portal is a site that presents a culmination of unrelated information in one place. Currently many popular search engines such as MSN and Yahoo also act as portals on the web. As portals evolved, they offered new features, such as the ability to save user preferences and other customizations. Users could configure portals to remember their settings, the type of information a user wanted to see next time, or the background color a user liked. Therefore users are able to arrange the information they want to see in portals as opposed to viewing what the website thinks the user should see.

The difference between a portal and a portlet container is that a portal is the user facing site of a portlet container. In early days portlets were written in-house, which meant that developers had to rewrite code that allowed users to move objects around on their portal interface and portlets written for one Java container were not compatible with others. However, in 2003, when Sun Microsystems released JSR 168, this situation was changed. The original specification, although not perfect, provided a standardized portlet API that defined portlet lifecycle and a number of other features. Today, most portlets and portlet containers adhere to either JSR 168 or the later JSR 286 specification, so portlets written for one Java container are compatible with other containers.