While texting on Wi-Fi, am i using data?

When i'm on my iphone with all cellular data turned off, using only Wi-Fi, my data isn't being used while texting, right?

Obviously Not.

If the other person has an iPhone and you are both texting over iMessage rather than regular texts then no you aren't using data. If you send videos pictures nothing will be charged since you are both using iMessage and have Wi-Fi.

Texting doesn't use data regardless.

And it's usually not done over Wi-Fi unless you have a texting app.

Plans include texting, data and minutes. They are independent from each other.