He was born to this world, received enlightenment, became Buddha and parinibanna* at the same time. And those moments were called as Vesak Day.
Buddhists don't celebrate this day like when Christians/Catholics'Jews celebrate Christmas etc, but they use this time to remember the life of Buddha, his teachings, and to introspect ourselves as human.
I'm really glad that I was taught formally about his teachings for almost three years in school.
I couldn't imagine what would I be if I didn't choose Buddhism as my religion for some reasons.
My mind keeps growing to be better, I'm more able to control myself now than three or five or seven years ago.
I don't know about whether my friends, my family notices but I'm feeling better now.
but I often do things awkwardly.....
(like you know, I said wrong thing or sensitive thing when people greets me, ask me whether did I able to do the test or something like that. It's just frightening me, okay. Misjudging and misunderstanding could burdened my life...)
*reached Nibanna/Nirvana; a state where we achieved the highest hapiness, a state of being free from dukkha, being free from rebirth in the next life after meditation or "purify" our mind to destroy all bad karmas we've done in our life or our past life, pass away or likely a euphemism for death.