Why is he called the identity?
Remember the multiplicative identity for regular numbers?
What can you multiply 3 by so he stays a 3?
It works both ways!
It's the same for our identity matrix!
By the way, this guy is the 2 x 2 identity:
So, what's the 3 x 3 identity?
The 4 x 4 identity?
*All identity matrices are square.