Device Detection vs. Responsive Web Design

We hear so much about responsive web design these days that it seems many of us have entirely forgotten that there are actually other options available to us—primarily what is known as device detection.

In a nutshell, device detection is when the web server hosting a site executes code to determine what type of device is hitting the website it hosts. Based on this, the site serves up files specific to that device. It might redirect the user to a mobile version, or it might simply serve up slightly different files.
The point is that the changes are happening on the server, and this reduces the burden on the user’s device. In theory, this makes the website much faster.
The biggest “gotcha” to this is the actual detection part. Fortunately, there are a number of specialized services (for example) that do nothing but just that. These utilities can be bolted onto your site and used to sort out what device and screen size the user is coming from.
Read more at HOW