Dreamweaver is one of the most popular web design tools that allows users to combine different media like images, text, and animations onto a website. It enables positioning and editing of graphical images, changing images on hover, and generating basic PHP code. Learning Dreamweaver online through courses is beneficial for anyone looking to become a web developer or designer, as it teaches how to manage images, use features like templates and code hints, and link websites to databases. Dreamweaver's abilities to preview websites during coding and adjust designs without moving code make it a very useful tool for web development.