The best times in one's life are the ones that have been spent in the past.

Everytime you think of one such time in your life, it evokes a nostalgic feeling.
As a human, we tend to forget the things that happen in our lives, both good or bad.

But a small glimpse of a photograph or a fleeting thought of something which reminds you of those good times sends you packing back in the past.
The feeling is superlatively special to you but you cannot share it with anyone because people, however close, will not relate to your nostalgia unless they have been a part of it themselves.
Picture
It's like a cup of hot coffee with a topping of chocolate sauce and fresh cream on a snowy day.
You are on a busy traffic median with traffic zipping past you in both directions... there you stand all unaffected with that cup of coffee and snow flaking on your shoulders... you look around dazed, but the surroundings don't affect you.
That's because the nostalgic feeling makes you numb to your present troubles.
For a moment, you forget whatever is bothering you today and just feel happy for that time that you spent in the past.
This is nostalgia.
No definition in any dictionary can define it.

A person could feel nostalgic about his high school cricket team..
About his crushes which never went to stage-2..
About college life.. hostel life..
About the first few days in your first job...
Basically just about anything that makes you feel happy..
Just a couple of days back i saw some pictures of a long lost friend on fb who was on some common friend's profile .. just remembered all the good times we had..
For that next 10-15 mins, the world's troubles could not touch me.

There are other kinds of nostalgias as well.. those that are invoked by listening to songs.
This, the Indian audience will appreciate.
In India, we have songs for every occassion. Some of them take you back in your memory lane and bring back all those good times.

'Live in the present' is a famous saying.. well, not always.
When you have time to introspect, have those few moments where there is just you and nobody else, it's an absolutely good idea to go back into the past.
It refreshes you like nothing else!
Try it out.

But, despite all that, its only a feeling which is virtual... which will make you feel good for a few moments.
It's not real. It 'was' real once upon a time.. not anymore.
Maybe that's why it's beautiful.

A famous song from a Hindi movie in the 1970s rings through my ears...
"Zindagi ke safar mein guzar jaate hain jo makaam woh fir nahi aate.. woh fir nahi aate"
--All the milestones that you cross in your life, will never come back.. will never come back.

But you can feel good that they came once in your life!