Isn't it strange how things seem the same from day to but when you look back everything is different? Children grow up, parents age and places change. Often, photographs are the best way to truly capture the passage of time.

There's something super nostalgic and wholesome about side-by-side then-and-now photos. Whether it's once-young lovebirds who've now become grandparents, a group college friends all grown up, or sibling babies entering their teenage years, these kinds of pics are the ones that make us wonder where on earth the time went.

r/PastAndPresentPics is a delightful corner of the internet filled with interesting, heart-warming and even funny photos of people then and now. Some are re-enacted or recreated, others are original. All are special. Bored Panda has put together a list of the best to remind you that time waits for no one.

Looking through photos of days and years gone by can often stir up deep feelings of nostalgia . And while this can sometimes bring us comfort and joy, it can also leave us feeling sad about what we've lost.

Interestingly, nostalgia was initially defined as a neurological illness characterized by a persistent longing for one’s homeland. It's a concept coined by Swiss physician Johannes Hofer back in 1688.

"It was not until the 19th century that nostalgia began to be seen as a positive sentiment, rather than a pathological condition," notes VeryWell Mind. But as we've already mentioned, nostalgia can be good or bad...

"Positive nostalgia is characterized by happy, rose-tinted memories of the past. It is often associated with feelings of warmth, happiness, and comfort," explains the site. "Negative nostalgia, on the other hand, is characterized by bittersweet or even painful memories of the past. It is often associated with longing, sadness, and regret."

On the plus side, feelings of nostalgia can help boost our mood, increase self-esteem, provide a sense of social support, help us to cope with difficult life transitions, such as divorce, retirement, or even the loss of a loved one.