Yes !! Definitely you can buy shares today and can sell it tomorrow but make sure that stock is not from T-segment, We'll need need to worry for that just try not to go with penny stocks for such practice (Penny stocks means share prices like 1 rs 0.50 paise and like that lowest rates )
Try for the Nifty 50 stocks ( Google it you can get the list )
When you are going for buy you can even sell it after a seconds also, There is no as such guidelines and restrictions. Same day execution of buying and selling means Day-trading.
you can sell them immediately if you wish. But due to stamp duty, the brokerage commisiion and the spread (the difference between the prices at which you buy and sell a share, the price at which you buy a share is always higher than the price at which you sell and this difference is called the spread), you might not make too much of a profit if you do this over a day or few days. In that case, the only one who will benefit from your frequent trading will be your stock broker.
However, if you are considering trading in CFDs or Spreadbetting, then it might be alright, for some highly liquid shares to do intra-day trading (buying and selling on the same day) or short-term trading (over a few days).