A network can be defi ned as groups of transmission links and the associated equipment that allow information exchange among the users connected by these links. Its application in PACS has improved radiology signifi cantly. For healthcare professionals, connectivity has never been as important as it is today, and this connectivity is dependent on the quality of hospital computer networks. Not every aspect of computer networking is covered in this chapter; only such technical components that are a part of the healthcare institution network are discussed with a view to understanding their applications and limitations.