Albireo, which is also designated Beta Cygni, is located at the southern end of the cross within the constellation Cygnus, and it's very well known as one of the most popular double stars in astronomy. When viewed with the naked eye, this looks like a single star, but even in a small telescope with modest magnification, it's possible to see that Albireo consists of two stars [1, 2]. The brighter star (which is labelled Albireo A) looks yellow and has a magnitude of 3.1 [3], while the fainter one (labelled Albireo B) is a blue-white star with a magnitude of 5.1 [4] that is similar to but hotter and 3.7 times more massive than the Sun [5]. The two stars are separated on the sky by a distance of 34 arcseconds, which is equivalent to the size of a large crater on the Moon. Both the wide separation and the contrast in colors makes Albireo a really popular amateur astronomy target, and if you go somewhere where someone has set up a telescope and where Cygnus is visible, they will almost certainly point their telescope at the star system and ask you to look at it. Some more enthusiastic amateur astronomers will actually demand that you look at it and won't let you leave until you do.
Anyway, you may have noticed that I have been calling this a double star and not a binary star, and that is because it is not entirely clear whether these two stars are gravitationally bound. If they were orbiting each other, they would be called a binary star system, but if the two stars just happen to be in the same part of the sky by chance, then the pair would be called a double star. The distances I have on hand indicate that the brighter Albireo A is located at a distance of 362 light years (111 pc), while the fainter Albireo B is located at a distance of 398 light years (122 pc) [6,7]. That implies that the stars are separated by 36 light years (11 pc), which would be much much larger than the distance between the Sun and some of the other nearest star systems, although the separation between Albireo A and B is less than 12 pc, which means that I get to use my Star Wars sound effects. Having said all of this, all of these distance measurements are relatively uncertain, so it's possible that the two stars are actually closer together [5]. Even if they aren't part of a gravitationally bound system, it seems like they are about the same age, and they as well as a few other stars in this region of the sky might have actually formed from the same nebula [5].
While we don't know whether Albireo A and B are actually orbiting each other, we do know that Albireo A itself is not just a single yellowish giant star but actually a triple star system. The first hint of this actually came at the end of the nineteenth century when people were just beginning to make spectra of stars, and a few people, including Antonia Maury at Harvard, noted that the spectrum of Albireo A looked like the spectrum of two different stars added together [8, 9]. It took until the second half of the twentieth century for people to be able to determine that the system indeed contained at least two stars [10, 11]. The brighter star, labelled Albireo Aa, is an orange-red giant with a mass of 5.2 times the mass of the Sun, while the smaller, fainter star, which is labelled Albireo Ac, is a bluish-white star with a mass 2.7 times the mass of the Sun [5]. The Aa and Ac stars are separated by somewhere around 48 AU, which would be slightly more than 1.5 times the distance from the Sun to Neptune, and the stars orbit each other once every 122 years [5].
The third star, labelled Albireo Ad, was not discovered until 2022. To make things interesting, it orbits Albireo Aa in a very tight orbit with a radius of 1.9 AU, which is larger than the separation between the Sun and Mars, and it completes an orbit once every 371.5 days [12]. The Ad star has a mass somewhere in the range of 0.035 to 0.085 times the mass of the Sun [12], which would make it either a really faint red dwarf or a brown dwarf, which would be an object too small to trigger the fusion of hydrogen into helium in its core.
By the way, you may have noticed that I did not mention anything named Albireo Ab. A few decades ago, a couple of different groups of people thought that they might have spotted another star in the Albireo A system, and it was given the label Ab [13, 14]. However, it looks like it might have been a false detection because no one has seen any sign of it since.
To wrap things up, I think I can say that Albireo is known as the go-to double star to impress people in amateur astronomy, while it's a dynamically complex system that has intrigued professional astronomers for decades, and while amateur astronomers are going to continue looking at this system for the pretty yellow and blue colors, professionals are going to look at it to try to understand how the A and B systems are truly related to each other.