arduino serial problem

Arduino is still sending signal from the serial port with no programs opened, any idea? because i noticed that i can use arduino serial communication only from arduino ide.

The Arduino board does not know that there is nothing connected on the other side. So if you tell it to send something, it will send something.

You can use any serial communication program to read the serial port on a computer and it will be able to receive the data.

You can obviously implement protocols. Arduino code sends command, receiving application replies. If there is no reply, Arduino code can know that nothing is connected.