“You may have heard about ISIS referred to as IS, ISIL, or Daesh. All of these acronyms describe the group in question.

ISIS: Islamic State of Iraq and Syria was the name of the group when it captured Mosul in 2014 and became the terrorist juggernaut it is today.

ISIL: Islamic State of Iraq and the Levant (aka Greater Syria) is the name that Obama uses to describe the group (pretty much only Obama uses it). Superficially speaking, it is just a translation thing.

IS: Islamic State is the name the group gave itself after a "rebranding" effort when they wanted to show off their global strategy (they wouldn't be limited to Syria and Iraq anymore).

Daesh: This is essentially the Arabic acronym of the group.”