What are synthetic vitamins composed of?

Hi, i'm not a doctor so cannot use technical terms,and would keep it simple.

These day, the large number of supplements in markets are present due to their demand because of degrading quality of food.

Supplements are either natural or synthetic.

Naturals one are from natural food sources and are supposedly absorbed & utilized best by the body as compared to some foreign entity.

Synthetic sources as their name suggests are synthesized are most obviously in a laboratory. They are taken from various chemical sources present in nature and binded together by using artificial coloring, coal tar derivetives, preservatives etc. (basically other chemicals).

For eg. vitamin C in labs is made bu using the base product as starch.