Life is what happens whilst youre alive.
Not to besmirch thousands of years of philosophy but its kind of a silly question really, though i suppose in a DP/R forum called 'thats life' its kind of inevitable that someone would ask it. Its a question i asked myself a thousand times as a teenager.
What is life? It can no doubt be defined scientifically although that may not be what Depersonalized is wondering about.
From my own experience i would definately add (to paraphrase someone), life is what happens when youre not paying attention.
Life is simply the time that we exist, a brief glimmer from a distant window into an expanse without measure.
Sometimes it is difficult not to feel that even the most accomplished individuals on earth are just poor bedraggled creatures clinging desperately to existence, huddled together on the surface of a hot sphere hurtling through the unimaginable depths of a cold unfeeling universe.
For some reason i often get this feeling when i read Shakespeare (but then its King Lear and Macbeth so..)
On the other hand, there is dancing and music, delicious food and wine, the scent of a summer breeze and the perfect vague things i dream though have yet to experience, poetry, exploration of the world and the measureless variety of the human experience, the joys of travel, possibly even love.
Plus everything else i havent mentioned. Positive and negative, Yin Yang. Thats life, if youre lucky.
To steal from Gandhi: Life would be a good idea.