there is a number of techniques that can be used to make webpages dynamic, e.g., give them content that can change. such pages either contain pieces of code in scripting languages (like javascript), are generated by scripting languages (like php, perl or python) - or even both. the difference is that websites containing scripts can be changed while they are loaded in the user's browser, whereas script generated pages are static when loaded, unless they contain scripts in turn.

databases come into play in various forms: in some cases, like with typo3 and similar content management systems, the contents of webpages are actually stored in databases and the pages created on the fly. in other cases, only parts of the pages are stored in databases - guestbooks usually work like that.

some recent technologies like ajax use a combination of script inside webpages and php script to retrieve data from databases: a php script is called by some javascript in a webpage, the php can be used to search a database and finally return the search result to the script in the webpage which in turn published it somewhere on the page.