So the Union Operation. So the Union Operation in Relational Algebra, that's the definition of it. So you have two relations, R and S, and you want to find the union of all the tuples that belong to R and S. So, if R has 10 tuples and then S has five, you go ahead and merge, like put all of these together, union all of them together into one relation, and that's the output of the Union Operation. So as you can see here, so we've seen before the two different tables or two different relations that were before. It's the student major from electrical engineering department and student majors from the computer science and engineering department. So they were two different relations, R and S. And the union of these two, we put them all in the same relation, and the output will be that way. So assume that this was a table, R and this one was the table, S. So these were before the Union they were two different relations. And then when we did R union S, it resulted into this relation. So generally speaking, when we talk about Relational Algebra, the output of a Relational Algebra operator, like the union for example, is another relation. So you union two relations and the output is another relation, mathematically speaking. Thank you.