In this instructable I'm going to show you how to connect your arduino to the internet, there are many ways to do this. One use an Ethernet shield but its wired and not very convinent to use ,on the second is wifi it may be the best way to connect to internet but wifi shields are expensive its around 80 dollars.
In this I'm going to connect arduino to internet using Bluetooth module and this would cost you around 5 $ . This is the best and cheapest alternative.
If you like my instructable vote for me

Step 1: Requirements

The nessary requirements is a cheap Bluetooth module from eBay HC06 , an android phone with an internet connection. You can buy the cheapest module for 4$ , search over eBay for HC06 . You should use an voltage divider before connecting it to the arduino. Reffer to the circuit for assembly.

Step 2: Android Setup

After you complete the previous steps its time to setup your android . Download an app from play strore named Arduino Bluetooth tether . And set up update time to every 1sec. Pair your android with your HC06 , the pairing code is either 1111 or 1234 . Turn on the app and connect your module.Leave the server URl to default if your using the attached examples or enter your server URL if you want to control your arduino using your own codes.
That's it your done.

Step 3: Example

Then create your own code and server using processing depending on requirements. Visit this
website for more details and examples- www.power7.net/
Chose a project you like and you'll find the sketch in the description.