Beginner's question: How to run a PHP web application locally?

Hi List, The other day, I read an article that mentioned about a tool that would permit to simulate a web environment for PHP, so that testing could be made before uploading the page on the server. Unfortunately, I don't seem to find the article again. So here am I with this question: What should I need to set my test environment? I'm working on Windows, but I'm all ears for solution on Linux systems. Best Regards, Bastien