Warrants represent an option to purchase a certain number of shares (common or preferred) at a future date at a fixed price, which can be the price of the current round of financing or set at a premium to the current price per share. (marsdd.com)
In some cases, a founder may want to transfer up to a certain number of shares each year without being subject to the ROFR / Co-sale. (startupcompanylawyer.com)
To counter this, you could use a tool like Social Warfare, which displays share buttons but hides the share counts until the article received a certain number of shares. (blog.bufferapp.com)