As you know that if you enter to raise the fund in Share Market your first step has to register in NSE/BSE then you have raised the fund by Public. Now, FPO is a process by which a company that is already publicly listed issues additional shares to the public to raise more capital. This is different from an IPO (Initial Public Offering), which is the first time a company offers its shares to the public.

Now, the question is why do company issue an FPO?
Raising Capital, to fund expansion, reduce debt, or for other corporate purposes. Increase Liquidity: More shares in the market can enhance trading volume. Diluting Promoter Holding: Promoters may want to reduce their stake for strategic reasons.

There are two types of FPOs in Share Market:

First FPO is Dilutive FPO, New shares are issued, which increases the total number of shares outstanding, thereby diluting the ownership percentage of existing shareholders.
Second FPO is Non-dilutive FPO, Existing shareholders (like promoters) sell their shares, which doesn’t increase the total number of shares but shifts ownership.
Usually, FPOs are priced at a discount to attract investors, which might temporarily reduce the stock price.
In a dilutive FPO, existing shareholders’ ownership percentage decreases.
In a simple word, if an already registered Company in NSE/BSE again needs the funds for whatever reason, then the Company has a right to again come Public, second time when the company will come to raise the fund by public i.e. called FPO.