Hello everyone,
I've visited a lot of websites, like Daniweb, and found effects on the sites pages that are really of a considerable design. I know it's becoming common, but I really get impressed at seeing such things. When you put the mouse cursor on some button it becomes highlighted immediately without the need to replace the image of the button with another one.
Also, there are the menus that appear on the top of each page.
So, I just wanna know... Is it done using Javascript or what?
Thank you.

Some mouseover effects are achieved with javascript but many with Cascading Style Sheet (CSS).

Menus can be manually coded on each page but a better way is to get a server-side scripting language such as php to dynamically insert them as each page is served. Javascript can insert menus after a page has been served but this approach is not common.