1. The idea of a website or service that offers a broad range of services such as e-mail, games, quotes, search, news, stocks, etc. While it would be impossible for a site to offer everything, the idea of a portal is to offer a broad range of commonly accessed services at one location, causing the user to visit the site more frequently and commonly stay for a longer period of time. The Yahoo home page is a good example of a portal.
2. Portal is also a popular video game developed by Valve.