Now a days computers are uses USB ports to interface external peripherals. If we wish to connect a microcontroller with computer or laptop means, we need to convert UART signal to USB compatible signal.
Here this circuit constructed by using FT232RL IC, USB port has only four pins as +5V, D-, D+, GND. (see USB tutorial) The FT232 ICs pin16 (usbDM) is directly connected with D- and pin15 (usbDP) is connected with D+ of USB port.
The pin1 (TxD) of FT232 should be connected with microcontrollers RxD pin and pin5 of FT232 should be connected with microcontrollers TxD pin. (microcontrollers TxD,RxD pin number varies depends on type of microcontroller).
Get datasheet of FT232 IC here
Driver for FT chip : http://www.ftdichip.com/Drivers/VCP.htm