Skype (pronounced /ska?p/) is a software application(應(yīng)用軟件） that allows users to make voice calls over the Internet. Calls to other users within the Skype service are free, while calls to both traditional landline telephones（固定電話） and mobile phones can be made for a fee using a debit-based user account system. Skype has also become popular for its additional features which include instant messaging（即時(shí)通訊）, file transfer（文件傳輸）, and video conferencing（視頻會(huì)議）. The network is operated by a company called Skype Limited, which has its headquarters in Luxembourg （盧森堡）and is partly owned by eBay。

  Registered users of Skype are identified by a unique Skype Name, and may be listed in the Skype directory [di?rekt?ri]（目錄）. Skype allows these registered users(注冊(cè)用戶） to communicate through both instant messaging and voice chat（語音聊天）.Voice chat allows calls between pairs of users and conference calling, and uses a proprietary [pr??pra???teri:]（專有的）audio codec（音頻編碼解碼器）. Skype's text chat（文字聊天） client allows group chats, emoticons(表情，圖釋）, storing chat history, offline messaging （離線發(fā)送信息）(since version 5) and editing of previous messages. The usual features familiar to instant messaging users—user profiles（用戶配置文件）, online status indicators[??nd??ke?t?z]（指示器）, and so on—are also included.