Termite swarmers are flying termites that are also known as "reproductives" or "alates". These flying swarming termites are an indication that the colony has grown big enough to create pioneers who will go out and start "new colonies". These swarmers or reproductives mean that the termite colony attacking your house is so well fed that it is getting too big to be limited to just your house. They want your neighbor's house also...
If you have swarmers or reproductive termites, you should call a pest control operator immediately. Make a note of the exit point where the swarmers come out to show your pest control operator.
I once witnessed swarmers exiting a home in Austin, Texas. They were exiting through the soffit and it was literally a thing of beauty notwithstanding the implication of damage that was being done by their colony mates. Each swarmer termite would come out and fly into the air and as soon as one was out, another was coming through the same hole and was out flying followed by another and another until hundreds of swarmers were flying around in the air. The swarmers going out of the same hole reminded me of World War II footage of paratroopers going one after another and filling the sky.
So if you have termite swarmers and they swarm on the INSIDE of your house, you are going to have a lot of insects to clean up. If you see swarmers flying, it will inevitably freak you out and you will get a can of Raid and start killing them. They won't last that long even if you did nothing because they are trying to mate in mid air and if they are unsuccessful, they will die in the open air. If they are successful and mate while airborne, the two mating swarmers will then burrow into wood somewhere and start a new colony.