Another reason can be seen by every person that each picture is a memory. Maybe a person will take many trips in his life, if you take many pictures in each trip, you will find it is just like a novel about your own life. When you are old, you will always recall many things that happened long before. At that time, I swear that you will take out the albums and "read" them with happy tears. You also can find how you loved the life and what a pleasant life that god gave you.
Above the two reasons, you can find it is very important to take a camera with your trip. And that is my choice when I am preparing for a trip.
