Mobile computing gives a learner the ability to engage in learning activities when and where they wish. This may be formal learning, where the learner is a student enrolled on a course in an institution, or informal learning, where they may be engaged in activities such as a visit to an art gallery. This entry emphasises the importance of portals to this learning environment, using the MOBIlearn project as an example. The MOBIlearn project intends to develop software that supports the use of mobile devices (smartphones, PDAs, Tablet PCs, and laptops with wireless network connection) for various learning scenarios, including noninstitutional learning. (MOBIlearn, 2005) The project has two primary objectives: • Develop a methodology for creating mobile learning scenarios and producing learning objects to implement them. • Develop the technology to deliver the learning objects to users via mobile computing devices such as personal digital assistants, smart phones and tablet computers. The pedagogic aim of the system is to provide users with the ability to engage in formal, nonformal and informal learning in a personal collaborative virtual learning environment. To this end four scenarios were used as the basis of developing the requirements for the system. These were a formal university course and a related orientation activity, a nonformal health care scenario and an informal scenario based around museums and galleries. The philosophy behind the MOBIlearn system is that it provides a set of interoperable services. Services should be able to communicate asynchronously using unstable communication channels (MOBIlearn, 2005). The primary component of the system is the Main Portal component. Central to the Main Portal component was the Portal Service (PO_POS) that represents the single access point for the user to all the services provided by the MOBIlearn system. As well as the Portal Service there are six other services that make up the Main Portal component.