 In this short section, let's have a look at some sets. Now, I can just use normal array and do a bit of set theory. Here, I'm going to do the union of two sets. Remember, it's two sets here, a sub one and a sub two, and I'm just gonna get the union. So you see the two sets here, they are just normal arrays separated by commas, all these values, a one and a two. We can execute this line of code and we have our two arrays. Now, I can use the union function. It takes the argument of all these arrays that I want the union of, and that just means putting these two together. But there you see, for instance, there's a three, there's also a three, so that would be only represented once when we do the union of these two. And there you can see the two of them together. Remember the intersection, those would be elements that are common to both, common to both of these arrays, and you see the elements one, there's a one and a sub one, there's a one and a sub two, there's a three, there are threes in both of them, there are two threes here and a sub two, and there's a four that is mutual to the both of them. The difference, it takes away all the elements that are in the second set, that are also represented in the first, and it takes them out of the first. Remember the Venn diagrams from school, that's exactly what is going to happen. Subsets, that is going to return a Boolean value for us, it just asks, is a one contained within a two? So, do we find that all of the values in a sub one are also in a sub two? And of course, in this instance, it is false because there are values, let's go up, there are definitely values such as an eight here, or the seven, or the six, or the five, for that matter, that are not represented in a two, so definitely a one is not a subset of a two. Now we've represented these as, we've represented these as arrays, but we also have this set notation, the set function in Julia. So I can very specifically say that something is a set, it still takes the square brackets, so there's still this array form inside of, and what happens with this set is the following, let's look at the numbers as one, two, one, two, three, two, one, so there's certainly repetitions of the twos and the ones, and when I use set, it is just going to get rid of all the duplicates, and that is why you would use the set function here as opposed to just using a normal array, that is really for just getting rid of all of the duplicates, and certainly in sets, we are interested in the values as they are, not as they are multiple, or used multiple times as we want them in an array. So if that is your requirement, use the set function. In the next video, in the next section on this lesson, we're going to have a look at tuples and how tuples differ in, how they are different from arrays.