This means that if you have a website design that includes rounded corners made with CSS (cascading style sheets), Firefox will show the rounded corners but Internet Explorer (IE) will not.  The same goes for other elements like transparency, shading or movement; one browser may have no problem at all with these though others do not support these elements so rounded corners will show up as pointed corners, etc.  Likewise, some browsers may load pages faster than others.

Each browser has many different versions, this presents problems for web designers as each version supports different elements so a web designer has to look at a website in each browser and then, look at it in the different versions.  Of course, the real fun is the website code has to be fixed so it looks right and functions properly in each version. They come out with updates on a regular basis, so your website could look and function fine one day and the next day be broken when a new update doesn’t ‘play well’ with your website code.  The Internet is always changing and when browsers updated themselves, they often stop supporting older and outdated website coding/practices so you can see this is a potential problem, especially if your website was built many years ago.

Most common browser in the UK:
-Google Chrome 
-Internet Explorer
-Safari
Most common browser in the USA:
-Google Chrome 
-Fire Fox
-Safari 
Most common browsers globally: