What makes a great logo?

https://www.youtube.com/watch?v=RBTiTcHm_ac
What does actually make a great logo? The team over at Vox recently went and spoke to Michael Bierut, the man behind Pentagram.
Bierut takes us through the three key types of logo: the pictorial, the wordmark and the abstract iconography.
[Source: Vox]