PLEASE SOS help - quaternions and 3d geometry

[DerChef]

Hello all forum members

My questio would be better placed on a forum for mathematics, but your electronic forum has already a board for maths and thus, here i go 

I am trying to understand 3d Geometry and i come to this thing named "quaternion". This gives me a head ache trying to understand it. Can someone give me an explanation please? Its a life saving...

[kammenos]

Would this help?

http://www.euclideanspace.com/maths/algebra/realNormedAlgebra/quaternions/index.htm