On the first day, the six hikers in our group sat in the dining tent asking each other the typical, polite introductory questions: Where are you from? What is your job?

Throughout the second day, our conversation became more relaxed and evolved to jokes and friendly bantering.

By the third day we felt comfortable enough to challenge each other's opinions and engage in deeper conversation.

And on our fourth and final evening together, I realized my time with these other five people-now good friends-was suddenly going to come to an end. We'd spent every waking moment with each other over the last four days, but we were going to part ways once we left Machu Picchu for Aguas Caliente, Peru.

It's the juxtaposition that travelers all over the world face every day: We meet people who become friends in such a short time only to leave without ever knowing if we'll cross paths again. Saying good-bye is a constant. Some of the people I meet are in my life physically for only a few days (or even a few hours), but many of them help define specific moments on a trip.

On the Inca Trail, for example, my husband and I were in a group of hikers that consisted of Matt and Bethany, an adventurous couple from Los Angeles; Klaas, a young 20-something nearing the end of his around-the-world trip; and Matias, a young businessman from Buenos Aires who was taking a week of vacation from the corporate grind.

Of the group, I think it's fair to say that Klaas was by far the most dynamic and outgoing. He'd been traveling on his own for nearly nine months, hopping from his home base in the Netherlands to India and Australia then over to South America for a tour of the continent. During his travels, Klaas had become accustomed to making conversation with strangers. His stories of scuba diving on the Great Barrier Reef and climbing mountains in Bolivia were enough to make me question the value of my 8-to-5 job.

My husband and I immediately bonded with Matt and Bethany, who, like the two of us, took every opportunity to embark on adventurous travels. They enjoyed hiking, biking and camping and had no qualms about taking off for a long weekend in the wilderness. While the guys bonded over altitude sickness, Bethany and I chatted about our upcoming travel plans. She and Matt were already thinking about booking a trip to visit Germany the following year, just as we were.

Matias watched and listened, generally taking a backseat to our constant chatter. But when we lured him into the conversation, he had fabulous stories to tell about the colorful city of Buenos Aires, a place where none of us had been but all of us longed to go. He was a guy steeped in the corporate world, and I quickly learned a cubicle is the same regardless of where in the world it is located.

The six of us certainly weren't the only people hiking the Inca Trail at the time, but over the course of four days, we created a bond of friendship unique to that time and place. We decided that together the six of us would reach the Sun Gate first, and then we made the choice to explore Machu Picchu as a group long after our guides had turned back. It only seemed natural to spend this time with my newfound friends.

Travel is fickle and fluid. It introduces people into our lives and sweeps them away just as quickly. Regardless of whether the six of us remain friends in the long run, though, the people I met on the Inca Trail will always be part of the memories that define Peru for me. And it certainly won't be the last time I have to say good-bye.