I am looking to know what to call and how to code a search filter similar to the one on this website in the light blue box titled "hey there!" : http://www.gradconnection.com.au/graduate-jobs/
I noticed that when you play around with the dropdown options that it doesn't change the page.
If you can think of any example code that would be brilliant, otherwise any suggestions on how to do this [preferably in HTML] would be very much appreciated!
That site is probably using AJAX. With JavaScript, you can listen for when someone changes the option in the dropdown, grab the option they chose, and (with AJAX) load the new content without the page having to reload.
It's a cool effect, but not something that can be done with static HTML.
If you feel like learning to use AJAX, and have a basic understanding of JavaScript, you should read up on this jQuery function. http://api.jquery.com/load/
Pretty simple to implement, actually. But it helps if you know basic JavaScript.