Stock refers to the unit that constitutes the capital of a corporation. This is the concept of dividing the company into several people.
In other words, the certificate of the owner of the company means stock.
And the person who holds this stock is called the 'shareholder'. You get the right to share the company's assets as much as you have.
The birth of the Inc. played a huge role in the development of the global economy and the innovation of human history. Buying stock and becoming a "shareholder" means millions of people will take responsibility for this company.
If you do business with your own money, you will be responsible alone if you fail. Then it won't be easy for someone to start a business with courage.
Also, if you do it with a small amount of money, you can't make a big business.