What will happen if we start to buy shares labelled day trading and if we dont sell it at the end of the day?

Suppose when the trading starts and if we buy some stocks labelled as day trading and if we are not satisfied at the rates and hoping that it will revise the next day,if we dont sell the shares what will happen?will the software sells itself at the end of the day or what?pl tell me iam new to online trading…. pl help….

If you set it at Good Till Cancelled (GTC) order, it will expire at the end of the following month. But if it was a day order, it will expire when the markets closed for the day.