What do all the Ds and Us mean in strumming pattern

many times i see strumming patterns like DDUUDDUU,DUDUDUDUU etc. wat do this mean

 

D : Down Stroke
U : Up Stroke
Commas and Spaces are intervals (momentary pauses)

 

well i am also newbie but i thought the ds---> down strokes and Us---> up strokes
the DDUUDDUU pattern means 2 time down stroke then 2 up then 2 down then 2 up.

and if you can't understand visit this till yesterday i was also don't know what strumming patterns are

https://www.guitar.gg/strumming.html
https://guitar.about.com/od/freebeginnerlessons/a/beginner-strum.htm