What is Mysql, and how does it help to make a dynamic website?

Almost any major website you visit has a DB backend of some sort. MySQL is the most common and popular. At least 3 out of 4 websites you visit use MySQL including some of the biggest out there. Postgres is a distant 2nd or third. Oracle is also used and a few sites even use SQL Server even though it's very poorly designed for use with websites and poses severe security problems.

MySQL is robust, quick, light on sever resources and either free or if you buy the commercial versions dirt cheap compared to Oracle or SQL Server.

There are quite a few front ends for MySQL. You should try out several until you find one that works best for you. Just Google MySQL front end or MySQL GUI and you'll find hundreds.

Yes links or even the entire image may be stored in MySQL. You can store just about anything in a MySQL table if you use the right data type. I strongly advise against storing images in the DB however. Instead store a path and let the image live on the HD itself. Far more efficient and much quicker that way. It's also a whole lot easier to code and maintain. Yes you can store entire web pages. I once wrote a db schema designed to allow people to create an entire web page on the fly. In seconds they were able to create a custom page tailored too a user.

The way a DB makes a website much more dynamic is you can have very rich data displays. Organize gigs of data and make them accessable to the user. You can create content based on user actions. Not just regurgitate you can create the HTML on the fly using a combination of PHP and a database. You prevent redundant data, use less space than if your using something really verbose like XML to store your data. MySQL is supported by all major backend scripting languages.

MySQL data types

http://www.htmlite.com/mysql003.php

Databases give you a powerful way of managing your data such as enforcing referential integrity.

If you have a user and you want to display the videos that that user has got then you query the transaction table for that users ID and display the records that contain that users ID.

You can store images but it is not recommended you are better of using a text field which acts as a link the the image location on a file sever.

http://www.datanamic.com/support/storeimagesinthed...

all major sites have an sql db, there are other types of databases aswell

(oracle, postgres, blah blah idk how to spell)

these databses are what holds the entire websites info (user accounts, posts, images, files)

anything can be stored in a database, except when people have big forums they usually move forum attachments out of the database and to a folder on the server.

content management systems (CMS) use databases to store all of your posts.

there is alot more to talk about but i just gave you the gist of it.