PHP is the scripting language used to create Joomla. So you can definitely use PHP in Joomla. The only question remains for what you want to use it!!
There are a few different ways to do it. Easiest is to include code using one of the 'custom code in content' extensions I use Sourcerer quite often, seems to work pretty well
off course, there is many extension to do it just search at extensions.joomla.org the plugins hope it help you
Their is a few extensions that will work. One is called "sourcerer" from nonumber.nl Another one, my favorite, is jumi. Find them at extensions.joomla.org
Hi.... If you want to use PHP in article or module, try change the editor from WYSIWYG to No editor. You could change it in the Global configuration or in the User manager or you could try extensions on this section on JED : http://extensions.joomla.org/extensions/edition/custom-code-in-modules There are a lots of extensons as you wish. hope this helps regards
for which purpose u want to use php because when u are creating article it is simple html page for login and registration u can use php but in article
Yes, you can. If you need to make a module as your page, joomla can help by by dafault. If you want to paste a script in the body of the article, you should install sourcerer module, to make this