It means that it was read by the person. I didn't know about that feature either till recently. I had this girl in my class who would always text me and i would just ignore her text. and she told me "why aren't your reading my txt!" lol. i asked her how did she know i wasn't reading them and then she showed me the whole check mark thing.
Okay okay..youre right caus all like 10 of the texts were just delivered at the same time. YOU are the MAN my friend..thanks for all of the help. She just texted me..So i guess she just read them. THANK YOU SPOOKY