Hard contacts are plastic but unless you have a very complex prescription that requires them you will get soft lenses, or you are real tight-arse as hard loses are a bit cheaper than soft. You can get soft lenses in a single vision lens, bifocal, varifocal, toric (astigmatism) and AFAIK any combination you like. If your prescription is changing frequently contacts allow you to keep up without having to invest in new specs every few months. The latest materials for contacts are Silicone Hydrogels that are nearly as O2 permeable as the surface of your own eye which makes for long term comfort. They are also as soft and floppy as an old man's do-dah so no more chance of damaging your eyes in an off than in glasses, probably less chance actually. I used to wear my monthly disposables for one month - day and night, bin them and put in a new pair for the next month. Great for long term travel as I only needed to carry what I needed plus a couple of spares. These lenses were super comfortable but over longer periods of time some intolerance builds up so I now remove each night and put back in again next day, nevertheless after about 5 years of more less continuous wear it is time to give my eyes some respite from contacts for a while. Anne still mostly wears hers for a month at time with no problem.
Next time you lot see me I will probably be in my new specs.