You may have heard the term "Responsive" or "Mobile-Friendly" website a lot recently, but what do we mean when we say that?
In basic terms, a responsive website is one that "responds" to best utilise the available width on whatever device it is being viewed on. This very website is responsive - if you shrink your browser window or view this site on a mobile device, you will find that it will rearrange itself to suit the space available. If you tried this with a site that hasn't been set up in this way, you'd find that the right hand side of the site just disappears and you have to scroll horizontally to see it. Additionally, you often find you have to zoom in on certain sections to read them properly.
To give this a bit of context, until recently, the trend in website design had been for them to get wider and wider as desktop monitors did the same. Naturally, the more space you can utilise, the more you can display one screen. However, as mobile browsing became more prevalent, this posed a problem to web designers. While their wide sites looked great on a widescreen monitor, when they were viewed on a mobile, it meant that a huge amount of scrolling was necessary. This often meant that the most important areas of the page were "hidden" off to the right and relied on the user horizontally scrolling to find it - not ideal on a mobile.
One solution to this problem would be to take sites back in the other direction and make them narrow again. However, while this would improve things on mobiles, it would seem like a backward step for desktop users that had become used to website filling the screen. Therefore, the answer was to start to make sites that are both of these things. When a responsive website is loaded, one of the first things the site will "ask" the thing loading it is "how wide are you"? Using a clever bit of code, it will then make sure that device is given the correct site layout for the width available.
Google have recently announced that it will be taking responsiveness into account when ranking websites for its search engine, so now is the time to make sure your website works well on all devices!