Why does this happen?

[drea43]

all text message consist of 160 characters per text. When you are typing a text notice when you get to 161 it says message 2 . when someone is sending you a text on a smartphone ordinarily it will continally type but some phones stop typing and they have to start whole new text to complete the original message Unsure of why it does that. My mom has Verizon and she gets a message that says this text will count as 2 messages Do you want to continue, Yes or No