Because PHP files are just plain text files you can use any editor to create
and edit PHP files. But even though you can use simple text editor like Windows
Notepad it is alot easier if you use an editor capable of syntax highlighting
and advance text manipulation. For a simple file like hello.php
syntax highlighting will do nothing good, but when you write long pages it's
alot easier to find mistakes just by looking at the text color.
Some editors you can use are :
Personally I like using Dreamweaver and Eclipse. I like Dreamweaver because
my PHP code is usually mixed with HTML, and creating HTML tables and forms
are just so easy in Dreamweaver. However, Dreamweaver doesn't support CVS
(Concurrent Versioning System) which is critical when running projects with
many programmers. So currently I'm using Eclipse for creating PHP files.
By the way Eclipse is a free software and the PHP plugin is also free. If
you have tight budget but in need of a good editor you should try Eclipse.