Web developers need to consider a number of things when they are creating websites, including how those websites will look, act, and work in all of the different common browsers. Since there are so many different types of browsers out there, it can add to the complexity of the development. Fortunately, a number of different tools from the browsers themselves can help the developer in his or her efforts.
Safari and Chrome offer webkit inspector to check to see how the site performs in their browser. Opera offers DragonFly, as well as widgets that can help developers. IE and Firefox have tools for developers to use as well. When creating a site, it is important that the developer checks to see how they perform in the different browsers, but they also have to consider mobile platforms today. With more and more people using mobile devices, they have to be sure the sites look and work properly there as well.