Plexiglass is a brand name. Acrylite and Lucite are other brand names. For small framed prints, .10" acrylic is fine, but once you get a bit lager, .125 (1/8th") would be preferable. You need to allow a little expansion/contraction room inside the frame rabbets. And it bows a little toward heat in larger applications. It being plastic, it's also electrostatic and attracts dust, so you need to peel the masking paper off in a clean environment and then treat the plastic with antistatic plastic cleaner, like Brillianize already mentioned, using a soft microfiber cloth with its lint shaken off or preferably rinsed out first.
The advantages of acrylic is that it's resistant to breakage and a good thermal insulator, discouraging mold growth on its inner surface. Acrylic also has a higher transmission factor than regular glass - it's clearer. The disadvantage is that it's pricey right now, and is susceptible to scratching or hazing if improperly cleaned. Unless you buy it precut, you need the right tools to size it. Small jobs can be done via a simple handheld scoring blade and steel straightedge, then snapping it. But production work is more involved, and you might need dedicated equipment.
I have my own framing digs and can easily handle any size of acrylic or even sheet glass up to six feet wide. I've worked with quite a few types of both, including expensive optically coated picture framing glass. I overwhelmingly recommend acrylic instead for most photo purposes. You don't need to be paranoid about shipping it. There is even an optically-coated reflection-free version of acrylic, but then you're talking very serious money.
I don't personally care for the muting effect to blues in color prints which UV-control acryics do (analogous to how pink skylight and amber 81A filters do shifts color film response). Nor have I found them taming the effects of UV all that much, certainly not as any alleged substitute for avoiding UV-rich display lighting entirely to begin with. But the previous post looks like a good resource to discuss and price your options.