Original: King Edward's Chair (or St Edward's Chair), the throne on which English and British sovereigns have been seated at the moment of coronation, is housed within the Abbey and has been used at every coronation since 1308.
Simplified: King Edward's Chair (or St Edward's Chair), is the throne on which British sovereigns sit when the crown is put on their heads. It is kept in the Abbey, and has been used at every coronation since 1308.