Full Idea
Externalists are principally interested in understanding what knowledge is, ..while internalists, by contrast, are principally interested in explicating a sense of justification ..from one's own perspective.
Gist of Idea
Externalists want to understand knowledge, Internalists want to understand justification
Source
Richard Foley (Justified Belief as Responsible Belief [2005], p.314)
Book Reference
'Contemporary Debates in Epistemology', ed/tr. Steup,M/Sosa,E [Blackwell 2005], p.314
A Reaction
I find this very helpful, since I have a strong bias towards internalism (with a social dimension), and I see now that it is because I am more interested in what a (good) justification is than what some entity in reality called 'knowledge' consists of.