A more thorough explanation:

A buyback is when a company buys back its own stock from the market. This reduces the number of shares available in the market, which can increase the value of each remaining share. The company offers to buy shares at a certain price, but shareholders are not required to sell their shares.

One reason a company might do a buyback is to prevent a hostile takeover. By buying back a controlling share of the company, the company can prevent someone else from taking control against the wishes of the board of directors.

However, some people think that buybacks are a form of market manipulation. To prevent this, companies must follow certain rules when doing a buyback, such as registering a specific day for the buyback and not being able to set the price of their offer.

Let's say that a company has 1,000 shares of stock outstanding. The company decides to do a buyback and offers to buy back 100 shares at $50 per share. If all 100 shares are sold back to the company, the number of shares outstanding will be reduced to 900. This can increase the value of each remaining share, since there are fewer shares available in the market.

Another example is if a company is facing a hostile takeover attempt. The company might do a buyback to prevent the other party from gaining control of the company.