Milky white discharge all the time ??

I always have white milky vaginal discharge. I had it a lot worse in my pubescent years and would always have to wear panty liners in my underwear every day. I just want to know exactly what it is and why it happens because it just feels like I'm leaking all the time and it's annoying to have to change my underwear a second time in one day from so much discharge. I'm not worried that it's something bad because it's probabaly very normal, just want to know why it occurs and so often.