It depends on the producer. It can be from a tree or synthetic, or there can be no cork at all.
Cork is made from a cork tree or cork oak. This is a variety of quercus which is the family of trees including the oak.
If the wine is an expensive wine, it will probably be ruined by a defective cork. An inexpensive wine will not be helped by a defective cork, but the damage is less noticeable. You will need to use a better corkscrew to remove the remaining part of the cork. You may have to strain the wine to get the bits out. Many taste tests have shown that there is no difference observed in the quality of wine with synthetic corks vs. natural corks. The plastic corks are quite inexpensive and do not break apart. Most wine lovers have an aversion to screwtops, but the fact is that screwtops are as effective at preserving wine as corks.
Cork
It keeps the wine up against the cork, which keeps the cork from drying out. When the cork dries out it will shrink and either let air into the bottle (ruining the wine), or fall into the bottle (also ruining the wine).
A champagne cork is made up of several pieces of cork, that are grounded and glued together, like the letter T. It is shaped like a regular cork, before it is put in the bottle. The mushroom shape that you see when you open it, is a result of expansion of the cork by contact with the wine. An analogy would be a sponge that expands.
If you are thinking about a 'wine professional' then a Sommelier
You pop off the cork on a wine bottle before you can drink it.
The wine goes bad.
The main benefit of a CO2 wine opener is the ease and speed with which you can open a bottle of wine. The opener injects a small amount of gas into the bottle with a needle through the cork which pushes the cork quickly out of the bottle.
I remember a friend had a wine bottle opener that inserted a hollow needle through the cork into the air space above the wine. Then the user worked a small pump above the bottle's cork. As pressure inside the bottle built, the cork began to rise out of the bottle. I had a cork crumble when I tried to use a corkscrew extractor. I attached a longer than normal inflation needle to a tankless air compressor. What was left of the cork popped right out without leaving any crumbled cork in the wine. So, I made a long inflation needle for a bicycle tire pump and tried it out on a new bottle of wine with a full length synthetic cork. The bicycle pump has a pressure gauge. The pressure registered 80 psi. just before the cork began to come out quite speedily. This was a standard glass wine bottle, not a bottle for champagne or sparkling wine. I looked around the Internet and found some have conducted tests and determined a 2 liter (plastic) soft drink bottle will burst around 120 psi. I would think a normal glass wine bottle would be stronger than a plastic 2 liter soft drink bottle.
the tapered part of a champagne cork before it is inserted into a bottle is like a wine cork cylindrical and uniform