Subset every third value in a vector

Exercise Type: Paraphrasing

Consider this vector:

x <- -100:99

This vector has exactly 200 elements. You received a chunk of (uncommented) code from a collaborator to process this:

result <- NULL

for(i in 1:length(x)){
	if( i%%3==0 ) result <- c(result, x[i])
}

Instruction

Part 1: What does this code do? Can you express it with human words?

Part 2. This code can be simplified using vectorization. Rewrite this chunk of code, without using either a for or while loop!