With more and more people using their tablets or smartphones to surf the Internet, it's important that your site looks at its best to these visitors. Sites that rely on 'pinch to zoom', because the content has been scaled down to suit the screen, look old-fashoined and uninviting - the last thing a website wants to be! You need to entice people in, not encourage them to leave!
The buzz word at the moment in web design is 'responsive'. Basically, it means that the website responds differently according to which device is being used to view the site - for example a large PC screen, laptop, tablet (e.g. i-Pad, Nexus7) or smartphone will show content in slightly different places, without making the text so small you can't read it.
In 2015, Google started to rank 'mobile-friendly' sites higher in search reslts (done on a mobile) higher than non-mobile friendly. As nearly half of all searches are done on mobile hones - can you afford for your website not to be mobile friendly?
If you're viewing this on a pc or laptop, drag the window narrower and you'll see the effect. Content is moved around to match the screen width.
The picture above shows how 121 Technology's old home page looked on different devices.
Firefox users can get the 'web developer' plugin, then select 'View Responsive Layouts'.
You can test your own site by following this link.