As we all know,Ruby Blocks and Ruby Methods work in tandem as clearly elucidated by the below example:

def demo_method
  yield "hello"
end

demo_method { |block_argument| "#{block_argument}!! our first ruby blog"}

here, the yield keyword within the method finds and invokes the block the method is called with.Alternatively , A less preferred way is to declare a parameter to accept the block in the method signature. Both examples given below are functionally equivalent:

def second_method &my_block
  my_block.call "argument"
end

def second_method
  yield "argument"
end

Coming back to the earlier example, block_argument  as its name suggests, is the block argument that holds "hello" in this particular case.

Now,consider each method of class Array:

2.1.5 :005 > ["a","b","c","d"].each {|block_argument| puts block_argument}
a
b
c
d
 => ["a", "b", "c", "d"] 

It is quite interesting to know the internal implementation of each method ,here it is:

class Array
  def each
    index = 0 
    while index < self.length 
      yield self[index]
      index += 1
    end
  end
end

here , self refers to the current running array object and we pass the current element of the array to the block as its block argument.

Within a method,in order to check whether the method is being called with a block or not ,we use block_given? method. Depending on the presence or absence of the block ,we can change method behavior accordingly.

Thanks a lot for reading.