As per Wikipedia, World Autism Awareness Day is an internationally recognized day on April 2 every year, encouraging us to take measures to raise awareness about people with autistic spectrum disorders, including autism and Asperger syndrome, throughout the world. I never knew the existence of any such day prior to the autism diagnosis of my son. 

I guess that is how things go. We are not bothered about things that do not affect us. I was no different. However, since the diagnosis, every day is Autism Awareness Day for me now.