Does it cost money to use iMessages on your iPhone?

So before i got an iphone i had an ipod touch and i used imessages with my email and everything.
then i got an iphone with a number and my friend just texted me using her ipod to my imessages
with the email. Does this cost money for me to send her messages?

What's iMessage I use only whatspp

With the iPhone you now also have the option of using it over 3G/4G in which case yes it will cost money. If over Wi-Fi, no.

No, imessages are always free, even if used internationally they are free. Facetime also…