Everyone knows what wavy hair is, correct? Some people want wavy hair instead of straight hair because the texture is absolutely beautiful! But, some wavy hair are very curly.
Example:

You could count this as wavy hair, but it's more of a curly hair. The ends are very curly, so it gets tangled a lot. But, wavy hair is in the middle between straight and curly hair. It not completely straight because it's not a straight line, it a wavy line.
Example:

It's not curly because it does not go in circles.
Example:

Drawing wavy hair is not hard at all. You just need to practice a few moves. Practice this:

After you practice drawing these lines, you are ready to draw wavy hair. Don't rush, because once you've seen how to draw wavy hair, and you're confused; it's your own fought for not practicing. Practice and practice! Guys, let me tell you one thing. *Whisper* Actually, I am a beginner at drawing wavy and curly hair too... When MadameMarauder asked to to teach her how to draw wavy hair, I was like, 'Oh my goodness, I don't know how to draw wavy hair either...' So let's improve together! I apologize, I was too loud. Keep this a secret, okay? How exactly am I supposed to teach you how to draw wavy hair when I don't even know how either? So don't tell anyone that! Stay tuned and wait for the next chapter!