Aside from the few fearmongers threatening the end of the world, the dawn of the new millennium felt, at the time, like entering the future.

Humans marveled at how far technology had advanced in the 20th century. Just under half of all American homes had the internet and were able to Ask Jeeves for the location of the nearest RadioShack and create bad AOL screennames.

The mobile phone was becoming less of a brick, and you could even play 'Snake' on one.

There weren't any social media apps to scroll through immediately after opening your eyes in the morning (and just before closing them at night).

Even Friendster, the often-mocked social network, didn't exist until 2002, and Facebook wouldn’t appear until two years later.

So how was everyone spending their time?

As Allen Kim and Breeanna Hare pointed out for CNN, they waited patiently for the news.

If you weren't reading the newspaper or sitting in front of the TV, you could go hours without knowing the latest crazy thing the president said.

In 2000, daily weekday circulation for newspapers in the US was estimated at nearly 56 million.

In order to document your life, you had to carry around an extra device: an actual camera; the concept of the cameraphone was still a few years away from becoming mainstream.

And Netflix was just getting started: it could recommend movies, give you three DVDs at a time, and let you keep them for as long as you wanted. “The dream 20 years from now,” CEO Reed Hastings said in 2002, “is to have a global entertainment distribution company that provides a unique channel for film producers and studios.”

But why do we feel nostalgic for these things? Krystine Batcho, Ph.D., a professor of psychology at LeMoyne College and a licensed psychologist, thinks that this emotional experience allows us to get a better understanding of our own selves.

"It helps to unite our sense of who we are, our self, our identity over time," Batcho said. "Because over time, we change constantly, we change in incredible ways. We're not anywhere near the same as we were when we were three years old, for example. Nostalgia, by motivating us to remember the past in our own life, helps to unite us to that authentic self and remind us of who we have been and then compare that to who we feel we are today."

This also gives us a sense of who we want to become in the future.

"The other way that nostalgia serves an essential psychological function is that it is a highly social emotion. It connects us to other people," Batcho added. "It does that [in] so many beautiful ways. In the beginning, when we're very young, it's part of what bonds us to the most important people in our life, our parents, our siblings, our friends. As we go through life, it can broaden out and extend to a wider sphere of the people we interact with. It's a social connectedness phenomenon and nostalgia is in that sense a very healthy pro-social emotion."

And online communities such as '2000s Y2K Childhood' only back up these words.