World Autism Awareness Day 2015: Why People Are Wearing Blue Today

World Autism Awareness Day has people (and buildings) going blue today.

Autism is a developmental disability that usually manifests around the third year of life, according to the U.N. Symptoms vary widely across the spectrum but generally include engaging in repetitive behaviors, and having difficulties with communication and social interactions.

It affects all ethnic, racial and socioeconomic groups, according to the U.N.

Parents are often the first to notice the symptoms, such as when a child doesn't make eye contact, according to the nonprofit Autism Speaks. Concerned parents shouldn't panic, but they should have a talk with their family pediatrician, experts say.