piyushkul1:
Its an sensor which gives analog values. I haven't decided on the web server yet. I want the arduino to send the value of the sensor via WiFi and store it in the server online. What's the best way to achieve this? Php,mysql?
Why do you want the Arduino to send the sensor values via wifi? Do you mean via wirelessly instead of wifi? There's a big difference. If the sensor Arduino has to be on wifi, it has to implement the whole TCP/IP stack, plus whatever encryption your wifi has. If you just need the sensor Arduino to send sensor data wirelessly to some kind of base station, that's much easier. There are a few examples of wireless modules that can send data wirelessly, and the receiving Arduino can use a wifi shield to act as the internet gateway for this data.
Some systems use a Raspberry Pi as the gateway, because it's better at logging data and presenting graphs of historized data.