Most people call any kind of screen enclosure lanai. Actually, a lanai is a screened in porch. It's usually installed under a existing roof or overhang, has an aluminum frame (white or bronze), screen walls and most of the time one or two doors.
Just like a screened front entry, Florida-glass (vinyl laminated screen) or kick plate (aluminum bottom plate) can be installed on the lower section of the enclosure for added privacy and protection.
Screening your back porch will allow you to enjoy Florida's nice weather without getting annoyed by flies, mosquitoes, no-see-ums (specially installing 20/20 screen), etc. It will make a great place for parties, barbeque's, or just a place to relax.
If you are thinking about screening your back porch give Juan Zorrilla Inc. Screen & Aluminum a call: 941-928-2296 (Sarasota, Bradenton, Venice area, FL.)