I have blond hair! It means my hair has low amounts of the pigment eumelanin.
Interesting, I thought blond hair would come from a lack of pigment. I have brown hair, do you know what pigment is in it?
Well, the amount of eumelanin determines the color of the hair. Low amounts means the hair is blond and higher amounts results in brown hair
Ok, understood.  And black hair I suppose have the maximun amount of eumelanin, right?
Old French "blund, blont", meaning "a colour midway between golden and light chestnut". It gradually eclipsed the native term "fair", of same meaning, from Old English "fæġer", causing "fair" later to become a general term for "light complexioned". This earlier use of "fair" survives in the proper name Fairfax, from Old English "fæġer-feahs" meaning "blond hair".
The word "blond" has two possible origins. Some linguists say it
associated with age.
Genetics and biochemistry of hair color.
Two types of pigment give hair its color: eumelanin and pheomelanin. Pheomelanin colors hair orange and red. All humans have some pheomelanin in their hair. Eumelanin, which has two subtypes of black or brown, determines the darkness of the hair color. A low concentration of brown eumelanin results in blond hair, whereas a higher concentration of brown eumelanin results in brown hair. High amounts of black eumelanin result in black hair, while low concentrations result in white