You generally cannot tell for sure by looking at someone
Autism is diagnosed by a qualified professional, not by appearance alone
Common signs may include differences in social communication
Common signs may include strong preference for routine or predictability
Common signs may include intense or highly focused interests
Common signs may include sensory sensitivities to sound, light, touch, or texture
Common signs may include repetitive movements or behaviors
Common signs may include difficulty with changes or transitions
Common signs may include literal interpretation of language
Common signs may include differences in eye contact or facial expressions
Common signs may include masking or copying social behavior to fit in
Signs can vary widely from person to person
Signs can look different in children and adults
Signs can look different in women, men, and nonbinary people
Other conditions can look similar to autism
The only reliable way to know is a formal assessment by a specialist