& or && operator in R

I will defend next Tuesday. To relieve my anxiety a little bit, I decide to blog a little bit.

I am confused about the operator & and && in R, which one should I use?

It turns out:
"The shorter ones are vectorized, meaning they can return a vector, The longer form evaluates left to right examining only the first element of each vector"

an example would suffice to explain it.
> x<-c(1:10)
> x
[1] 1 2 3 4 5 6 7 8 9 10
> x>8
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE TRUE TRUE
> logical1<- x>8
> logical2<- x<5
> logical1
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE TRUE TRUE
> logical2
[1] TRUE TRUE TRUE TRUE FALSE FALSE FALSE FALSE FALSE FALSE
> logical1 | logical2
[1] TRUE TRUE TRUE TRUE FALSE FALSE FALSE FALSE TRUE TRUE
> logical1 & logical2
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
> logical1 && logical2
[1] FALSE
one can subset the vector by the logical vectors:
> x[logical1]
[1] 9 10
> x[logical2]
[1] 1 2 3 4