There is a company that I am pulling data from which has a unique ID for each record. However, the ID is alphanumeric (even contains a special character too). When I asked about this I was told that this is because the leading alphanumeric portion indicates the type of record that it is. Is this a proper format to use? I would have thought it would be best to just have a type column. 
Is it good form to use an alphanumeric unique ID?
coding style;database design
There is nothing wrong with alphanumeric IDs as such - they can be shorter, which is big advantage when they're handled by humans.Encoding the type in the ID is certainly not good from a DB design point of view, but it can make sense as a business requirement, again for human handling.I think the crucial point is that externally visible IDs are often subject to other requirements than only those of proper database design.