As you've learned in previous chapters, the symfony framework is a set of files written in PHP. A symfony project uses these files, so installing symfony means getting these files and making them available for the project.
Being a PHP 5 framework, symfony requires PHP 5. Make sure you have it installed by opening a command line and typing this command:
> php -v PHP 5.2.0 (cli) (built: Nov 2 2006 11:57:36) Copyright (c) 1997-2006 The PHP Group Zend Engine v2.2.0, Copyright (c) 1998-2006 Zend Technologies
If the version number is 5.0 or higher, then you're ready for the installation, as described in this chapter.
If you just want to see what symfony is capable of, you'll probably go for the fast installation. ...