DATEADD and DATEDIFF

I always try to remember these functions but for some reason end up going to MSDN to find the actual function name and syntax.

DATEADD (datepart , number , date )
select DATEADD (mm, 1, getdate())

DATEDIFF ( datepart , startdate , enddate )
select DATEDIFF (hh, getdate(), '2013-04-16 00:11:11.00')

Table below is from MSDN, just to you everyone an overview of possible option to use 
with these functions (along with any other DATE functions)

    

   
datepart
   
abbreviations
  
   
year
   
yy,   yyyy
  
   
quarter
   
qq,   q
  
   
month
   
mm,   m
  
   
dayofyear
   
dy,   y
  
   
day
   
dd,   d
  
   
week
   
wk,   ww
  
   
hour
   
hh
  
   
minute
   
mi,   n
  
   
second
   
ss,   s
  
   
millisecond
   
ms
  
   
microsecond
   
mcs
  
   
nanosecond
   
ns
  

Hope this helps and as always good is my friend....