increasing the number of shares is called as stock split.

Example:

if you have 100 shares, per share is 100Rs. then your portfolio is 100*100=10000.
Stock split means decreasing the share value but increase the number of shares. If share value decreased to 25Rs from 100RS. You can get 4 shares for 100Rs. so your no. of shares will increase and it is same to the existing portfolio. there is no change in the portfolio value.only the no.of shares will increase. then 400 shares * 25Rs = 10000.

A stock split or stock divide increases or decreases the 
number of shares in a public company. The price is adjusted 
such that the before and after market capitalization of the 
company remains the same and dilution does not occur. 
Options and warrants are included.

The words share split and stock split are same meaning. 
Types are Stock split and Reverse split.

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