The time-integrated amount of data and stored information, is doubled roughly every eighteen months, and since the majority of the worlds information is stored in magnetic media, the possibility to write and retrieve information in a magnetic material at ever greater speed and with lower energy consumption, has obvious benefits for our society. Hence the seemingly simple switching of a magnetic unit, a bit, is a crucial process which defines how efficiently information can be stored and retrieved from a magnetic memory. Of particular interest here are the concepts of ultrafast magnetism and all-optical control of magnetism which have in recent decades become the basis for an intense research field. The motivation is natural; the mechanisms behind these phenomena are far from trivial and the technological implications are huge.