Diffuse, Bump map, Specular and AO

i wanted to try and understand more about types of maps in maya i found it quite confusing understanding what each one does.

the diffuse map or colour map in the bottom rite hand corner is my basic texture which i copied different images from the internet and also hand painted them on Photoshop to get the effect i wanted.

bump maps is the purple looking one this adds great surface detail to a model without affecting the topology of the mesh. The map is generated from a 2d bump map.

specuclar map is used to define both the colour and strength of the specular reflection highlights.

AO maps give shadow to my model focusing on different surfaces to generate a shadow.