[R] Why are integers coded as e.g. "2L" in R functions?

[Alexander Engelhardt]

Hello R-help,

I keep noticing R functions that don't compare integers like
   if(x == 2)
but instead
   if(x == 2L)

Is this a long integer? Also, when do the two notations have a different 
effect on the code?

Thanks in advance,
  Alex