Could you explain why do i have a white spot on the bottom corner of front tooth?

Erosion: Possible wearing away of enamel due to using a hard tooth brush over the years-possible mottled enamel from Fluoride in water in excess of more than 1part per million or even a wearing away of enamel from having worn braces..

Decay possible: This could be a few things. It could be enamel decalcification, where the tooth enamel is weakening or eroding, and is the beginning of decay. It is something a dentist can diagnose and let you know how to treat it.p

Most Likely: it is the result of a viral infection that occurred while the enamel of that part of your tooth was being formed. Think of it as a birthmark.

White spot: Could be decalcification (early decay), developmental defect, genetic mutation. Ask your Dentist to check it out for you.