There is microprint, or tiny, clearly defined text, in multiple locations on the banknote.
Fluorescent Ink
A bird, the serial number and year of print fluoresce under UV light.
To validate the UV fluorescent features on Australia's banknotes, it is recommended that a UV black light with a wavelength that is centred around 365nm be used, and that it is done so in low ambient lighting conditions. Many UV black lights that use Light Emitting Diodes (LEDs) emit wavelengths between 395–400nm, which are not suitable for viewing the UV features