In Ruby, what does the Puts "a = #{a}" do?

Question

I can't figure out what the #{a} does, or what the # does. Here is the full code:

a = 0
until a > 10
puts "a = #{a}"
a +=2
end

Answer 1

#{any_variable} inside the string just added value of this variable to string.
i.e.:
a = 8
puts "a = #{a}"

# result: a = 8

Answer 2

oh gotya its like %var% in batch code!

By the way this was a comment off of Spiil hellig's comment