Blue light is primarily emitted by sunlight, and we are mostly exposed to it when we are outside during the day. But there are many other sources of blue light, including LED lighting, mobile devices, tablets and other screens..
The particularity that interests us for our eyes are the frequencies
below 380nm on the blue side (Ultra-Violet-UV). These rays, invisible to the human eye, are of very short wavelength and very energetic. We all know the importance of sunglasses and sun cream that we apply to our skin to avoid the harmful impact of UV.
On the other side of the light spectrum, the rays above 700nm (Infrared | IR) are also part of the invisible light but are not as energetic as UV. Paradoxically, these rays (IR) produce heat but do not modify the DNA structure of our cells, unlike UV. For example, in the sun you feel the value of IR but it is the UV that gives you sunburn impacting your skin's health.