Military Tuition Assistance is a benefit paid to eligible members of the Army, Navy, Marines, Air Force, and Coast Guard. Congress has given each service the ability to pay up to 100% for the tuition expenses of its members.
Each service has its own criteria for eligibility, obligated service, application process' and restrictions. This money is usually paid directly to the institution by the individual services.
TA is not a loan; it should be viewed as money you have earned just like your base pay.