What is Pilates?
Pilates is a method of exercising using spring-loaded equipment. Originally named Contrology and developed by Joseph Pilates circa 1923, the Pilates method has continued to evolve beyond its originator and inventor.
Contrary to popular comparisons, Pilates most closely resembles strength and conditioning training, not yoga.
What to expect?
Expect to move through short sets of specific exercises throughout your whole body within each Pilates session. You'll finish feeling like you've used every part of yourself.
Expect to have your movement habits noticed and a discussion prior to beginning any Pilates program. The guidance provided will be individualized to your specific goals and time spent to ensure your understanding. 
Pilates can be a way to begin paying attention to your physical experience and shift those movement habits that no longer serve you.
What to wear?
Plan to wear something you can sweat into and move freely in.
Avoid zippers, buttons, tags, and hoods if you can. We roll around some times!
Tight clothing is unnecessary, however, single layers allow your teacher to easier assess your body movement visually. 
Men should consider longer shorts, like boardshorts, or wearing boxer briefs underneath looser short shorts.
What is Pilates equipment?
There are 3 main pieces of Pilates equipment that are found in most studios and several auxiliary pieces. 
The Reformer is a moving carriage spring-loaded from below inside a frame of steel or wood. The lowest weight-bearing of these supports 300lbs. Considered the most user-friendly for beginners learning the Pilates method.
The Cadillac is basically a raised bed with a steel frame canopy from which springs can be attached for open-chain exercises amongst others. Most will support up to 250lbs hanging from their canopy and significantly more lying on their bed, which is where most exercises occur. Highly versatile, most studios have at least one of these for private sessions and individualized work.
The Wunda chair offers a smaller base of support with a spring-loaded pedal. Supporting up to 250lbs standing atop the chair, the Wunda chair can offer a challenging repertoire or incredibly precise focal practice.
Other equipment includes barrels, ladders, small props, weights, rollers, and ped-a-pull.