What Do These Messages Mean?

What do these messages mean? What do these messages mean? 1 R U OK? 2 C U B4 5 3 Gr8! 4 I’ll B L8! 5 I O U 6 Y R U L8? 7 W8’n 4 U 4 ½ hour  Are you OK?  See you before 5 00  Great!  I’ll be late![.]

What these messages mean? R U OK?  Are you OK? C U B4  See you before 5:00  Great! Gr8! I’ll B L8!  I’ll be late! IOU  I owe you Y R U L8?  Why are you late? W8’n U ½ hour  Waiting for you for half an hour