MON in front of a masculine word (singular) eg : MON ami, MON, vélo, MON crayon, MON livre,... MA in front of a feminine word (singular) except when the word in question starts with a vowel or a mute H. eg : MA copine, MA voiture, MA maison,... BUT.....MON Amie, MON Auto, MON Habitude,... MES in front of a plural word whether it is masculine OR feminine. eg: MES amis, MES amies, MES copines, MES livres, MES crayons, MES habitudes,...

"MA" is the feminine form of "MY" "MON" is the masculine form of "MY"

In addition to the good explanations below, I would add that French grammar is closer to Spanish grammar. Those possessive adjectives work more like in French than in English... I learned that while studying Spanish many years ago! :) (you know, "his/her father" vs. "son père", "his/her mother" vs. "sa mère"). I hope this helps you, rather than confuse you! :D