Considering how ubiquitous the internet is in most people's lives, it seems amazing that a full 15 percent of Americans still don't use the Internet on a regular basis, nor do they have it in their homes. This comes from a recent study by Pew Research Center, which has been tracking Internet adoption since the turn of the century, and it found that the number of people with access has stayed roughly the same for the past three years.

The last change to internet adoption came between 2012 and 2013, when just 1 percent more people ended up online than the year before. Since then, it's sat at just over 84 percent, with little sign of it increasing, despite efforts by the government and other organizations to continue increasing adoption.

This might seem surprising considering the prevalence of smartphones and social networking tools like Facebook, but there does appear to be a section of society that has not embraced the Internet like much of the rest of the developed world.

Looking into Pew's statistics, it appears that there are some trends that tie those outsiders together. For starters, the more educated a person is, the more likely they are to use Internet-based resources. Those with less than a high school education are much more likely to be nonusers, but even then only a third don't have some form of online presence.

Age is also a big factor, with a lot of those in older generations choosing to forgo any form of Internet access. In fact, two out of every five adults over 65 don't use any online tools at all.

The other big group without internet seems to be those that may struggle to afford it. Currently one quarter of households that collectively bring home less than $30,000 don't use the Internet either.

It seems likely that there will always be some segments of society that prefer to stay off the grid, but it's hard to imagine how with how much we use the Internet for. Even a few hours of downtime can be a nightmare for some, especially those of us that use it for work.