A new issue of a security is the sale of newly issued securities to investors in order to raise money.
New issues are economically the most important function of capital markets. They allow issuers to raise capital that they can then can invest in their business or use in some other way.
Without new issues companies could not raise money to expand and borrowing by all organisations would be limited to bank debt.
The number of, and the success, of new issues of different types is frequently used as a measure of the market sentiment. For example, if there are a lot of IPOs, it is an indication that investors are confident enough to put money in them, and that the market is high enough to tempt the owners of private companies to list. A lot of rights issues often means that many companies are financially weak.