Linux Apache MySQL PHP + Bitcoin tutorial.
For this introduction we assume that you have GNU/Linux server with Apache and PHP and that you wish to interact with the Bitcoin network from a web application. We assume some knowledge of Bitcoin and experience in PHP.
While this is written for PHP, the same principles apply for other languages. See the associated API reference pages for info on other languages.
The easiest way to get started is to run Bitcoin in daemon mode with which PHP communicates via local HTTP requests. A library called JSON-RPC is used to call the various functions of bitcoind, which will respond back with a JSON object.