What are home assessment fees?

[STI Jaguar]

Thanks, I've never owned a home so I am only getting used to the terms. I thought that it was interesting and I need to beware of the hidden costs beyond just the selling price. Some condos especially in the downtown area have assessment fees as high as $900, and some others a bit further away are $250. That is a large discrepancy assuming that both condos are of the same price.