Check the watermark
Check the security thread
Check for color-shifting ink
Feel the texture
Look for raised printing
Hold it up to the light
Check the microprinting
Use a counterfeit detection pen
Compare it to a known genuine bill
Check the serial numbers
Verify the holograms or other special features
Use ultraviolet light if available
Inspect for blurry images or uneven borders
Confirm the denomination and design match current currency standards