The open windows of the house were our enemies when we moved in. No screens meant every flying or skating or zipping thing could find its way through our windows and into our place. We shuddered in primal (or effeminate?) dread at the thought of the creepie crawlies and kept the windows closed. Besides, our gallant protector and chosen companion, the kitten Felix, might've seen the open window for the invitation to terrorize the other cats in the neighborhood. She wanted to attack them through closed windows - that open hole meant a certain mauling for some tom or curious kitten that decided to look in on us. But keeping the windows closed all the time made the place a kind of stagnant box. No circulation, no wind, no breath of the outside.
Two trips to Home Depot later, with scarred hands and little metal screen shards on the porch, we managed to make screens for our windows. Does that mean we're now be-screened? Or just screening?
Regardless, we now have a way to admit the air without the creepie crawlies. We now have a way to keep the cat in and hopefully circulate some of the air out.
A word of advice: never ever rent a place without screens.