For the complete article see the printed version in Encyclopaedia of Portal Technology and Applications

In general, portals are regarded as gateways to networked information and services, facilitating access to other related sites. Typically, portals provide transparent one-stop access to functionalities needed in a common context and make these appear as a single integrated application. Although these functionalities are implemented and made available by heterogeneous applications, they are integrated by presenting the output of such networked applications side-by-side, with only limited interaction between them. This superficial integration on the presentation level is quite useful, but it has considerable drawbacks compared to basing portals on the notion of subjects to achieve “seamless knowledge” and the “semantic superhighway” (Pepper, 2004, 2006; Pepper & Garshol, 2004).