When a company splits its shares, it is called a stock split. When the shares of a company become too expensive then the company is a stock split cutter so that small investors can invest in those shares. It can be 1:1 or 1:2. 1:1 means that if you have 1 share of that company then you will get 1 more share on that share, in the same ratio the share price will also decrease. Now you will have 2 shares.