A web portal is the main access point for multiple information channels. It can include clickable information to categorized information, such as content, rich topics, products, merchandise, customers, etc.
Often visitors have access to RSS & news feeds and other kinds of information that the web portal pulls from multiple channels and then displays in one centralized place. You can think of it as a hub for information and communication.
Web portal development requires several more advanced site-building skills, including rich application development, client-side and server-side scripting, registration systems and more.