We have heard about how ISIS is recruiting foreign fighters to join its ranks. But it's happening on the other side as well.
Just last week, a Massachusetts man who died fighting against ISIS in Syria was laid to rest.
Last year, a British man who calls himself Macer Gifford left his job as a financial trader in London and went to join the Kurds and fight the self-declared Islamic State in Syria.
Gifford spoke on the condition that NPR not reveal his real name, because he fears for the safety of his family in the UK.