I brought a ESP8266 module from eBay. The whole purpose was to do some experiments with it and understand how to use it in my micro-controller projects. I was not interested in XBee products since those were much more expensive than ESP8266.

Initially I started with issuing AT commands from my laptop to the WiFi module. To do this I brought a USB to TTL serial adapter.

Pairing ESP8266 and the USB-TTL adapter wasn't very simple , due to two reasons

1. ESP8266 may draw around 300mA in high power modes, but the adapter was capable of providing max of 150mA 3.3V.
2. WiFi module and serial adapter are working on different Logic levels (ESP8266 - 3.3V and USB-TTL - 5.0V )

In order to solve these issue I used a 3.3V regulator to provide  3.3V and enough current and few resistors to reduce the logic level or USB-TTL adapter. Below diagram show my configuration.

I chose arduino serial monitor to interact with the module with below configuration.
Line mode = NL & CR Baud Rate = 9600

AT Commands can be found on below documentations
http://woodsgood.ca/projects/wp-content/uploads/ESP8266ATCommandsSet.pdf
http://rancidbacon.com/files/kiwicon8/ESP8266_WiFi_Module_Quick_Start_Guide_v_1.0.4.pdf