Drain
Because basement are situated underground, their are prone to moisture infiltration and water damage. Besides water damage, basements are prone to rot and mold damage. Concrete is a very porous substance that will allow water vapors to pass through it.
Drainage
Drainage systems are very common in places where water represents a problem. There are both outdoor and indoor drainage systems. In the outdoors, these systems use trenches and channels to lead the water away from homes, garages, and basements. Indoors, these systems use sump pump to carry away the water and perforated pipes to collect it.
Materials
The best way to protect you basement is to build the drainage system as you build the basement. You can add special solution/additives to cement walls to increase water protection. For cracks around the walls and floors you can use foam insulation or hydraulic cement and epoxy patches.
Vapor barriers
Vapor barriers do not need to be installed in you basement, but on the exterior walls of your house and on the foundation. These barriers prevent moisture from accessing your walls and thus the basement. These vapor barriers are rolls of plastic and fibers that can be laid on concrete walls and basement floors.
Moisture sealers
Sealers are also vapor barriers, but are not as effective as construction materials. They are usually found in spray or paint form and can be applied directly on the walls. The main advantage is that they are easy to apply and they can applied even after the construction of the basement.