I think of shares on the stock market. A given company may never sell more shares than a set amount, and their shares may become worth a lot more, but they can simply split the shares, meaning that people can buy fractions of shares, which are now of the same value as what the shares were worth before.
Not true, afaik.
Companies issue new stock. The reason it doesn't devalue previous shareholders is that those shareholders now own a smaller part of a company that has more cash, in exact proportion to the dilution.