After almost an entire year without the Dowager Countess (that's Maggie Smith to you uninitiated) throwing shade, Downton Abbey returns tonight on PBS. It airs at 9 p.m. Eastern.

When we last left Downton, our favorite aristocrats had just learned about jazz music, interracial dating, and businesswomen. This season promises more of the old drama, along with some new.

But Downton Abbey is much more than a television show. It's a cultural touchstone — a gif-able, meme-able, hate-watch-able series with all the trappings of BBC royalty. If you're not up on your Downton knowledge, here's a brief guide to help you enjoy the premiere of season five.

1) What is Downton Abbey?

Downton Abbey is a period drama produced by Carnival Films. It can be viewed in the US on PBS, as part of its Masterpiece series. The series follows the lives of the Crawleys, the aristocratic family who lives in Downton Abbey. Their story began in 1912 and has continued to the '20s. Season five begins in 1924.

The Crawleys are waited on by Downton's servants, most of whom care greatly for the nobility they serve. The show is inspired by the 1970s BBC series Upstairs, Downstairs, which told the story of how upstairs nobles interacted with downstairs servants.

The series takes as its starting point actual historical events, including the sinking of the Titanic, and the assassination of Archduke Ferdinand, then filters them through the characters' reactions. The drama comes from the characters trying to navigate their rapidly changing, post-Edwardian world.

2) Is Downton Abbey a real place?

Though Downton is fictitious, the estate at which it is set and filmed is real. It's called Highclere Castle, and it's located in Hampshire, England. The Victorian home, set on 5,000 acres of land, is the country seat of the 8th Earl and Countess of Carnarvon, whose family has lived in Highclere since 1679. The castle has served as a filming location for several other series and films and is open to the public for tours.

Though much filming takes place at Highclere, some scenes — specifically, those taking place in the kitchen and the servants' quarters — are shot at Ealing Studios.

3) What famous actors are in the series?

This show pretty much stars dozens of familiar actors. The show's big name has always been Dame Maggie Smith, whose 60-plus-year career has included work on Broadway, the West End, film, and television. Smith is 80 years old and just as versatile as ever, with a keen ability to portray everyone from Downton's snarky Dowager Countess to Harry Potter's Professor McGonagall.

Many of the series' actors have played roles in notable films. To name two, Hugh Bonneville (Lord Grantham) has appeared in The Monuments Men and Muppets Most Wanted, while Michelle Dockery (Grantham's daughter Mary) appeared in the recent Anna Karenina.

4) Can you give me a general overview of the four seasons that have already aired?

Downton Abbey is an ensemble show. As opposed to having a cast of two leads and several supporting characters on the periphery, almost every character is given an interesting, complicated story. In essence, the series is a soap opera — though a big-budget, beautifully-acted one.

Therefore, summarizing each season in a few short sentences is difficult. With that said, here are the basic narrative shapes of the first four seasons.

When the first season opens, Lord Robert Grantham learns that the heir of his estate has died aboard the Titanic. Robert has three daughters, and the law of the land dictates Robert pass Downton to a male relative — which means he can either pass off his wealth to a male he barely knows, or have his eldest daughter, Mary, wed a distant male relative, ensuring his fortune stays in his immediate family. The male relative's name is Matthew, and his working-class tendencies — he's a lawyer — at first rub the Granthams the wrong way. Mary's two sisters, Sybil and Edith, look for love of their own, with the former beginning to warm up to Tom Branson, the family's chauffer. Several servants pursue love, too, the most notable being housemaid Anna and valet Mr. Bates. After Mary admits to herself that she's in love with Matthew, the season ends with Lord Grantham announcing that England is at war with Germany. The backdrop for season two is WWI, which has affected Downton substantially. Matthew, as well as house staffers Thomas and William, are enlisted to fight, and the Granthams agree to turn Downton into a convalescent hospital for wounded soldiers. Matthew's mother, Isobel, who has training as a nurse, clashes with Lady Grantham over how Downton's hospital should be run. Matthew returns to Downton on leave to visit everyone — and to introduce them to his new fiancee, Lavinia Swire. But though Mary's romantic dreams are dashed, Anna's are poised to come true, after Bates proposes to her. However, the elation is short-lived because his ex, Vera, shows up. Meanwhile, Sir Richard Carlisle, a rich newspaperman, has his eye on Mary, but she doesn't return his fawning. But when she learns that Bates's ex is planning on leaking a story of a great Downton scandal, Mary offers Richard her hand in exchange for his help in silencing Vera. Matthew, meanwhile, returns to war with William, and the two are badly wounded in battle: William dies, and Matthew is crippled from the waist down, rendering him unable to produce any children for Lavinia. He calls off the engagement. But this being Downton Abbey, Matthew ends up getting back his mobility and falling in love with Mary, just as Lavinia dies of the Spanish flu. Sybil decides she's in love with Tom, the chauffeur, and Bates's wife curiously dies in an alleged suicide. Mary breaks up with Richard. Matthew proposes to her. It snows. They kiss. It's perfect. The war is over, but Downton's troubles are just beginning. Robert discovers a major investment has failed, and his family is now close to bankruptcy. Mary and Matthew's wedding will be the last hurrah at Downton. But happily, Matthew has been left a fortune from Lavinia's father, and uses it to save Downton from financial ruin. He then becomes a co-master of the estate. Sybil and Tom Branson come back from Ireland, even more politically vocal than they were before they left. Branson helps run the house, and Sybil becomes pregnant, eventually dying in childbirth. Edith finally thinks she's found marital love, only to become stranded at the altar. This season isn't a total bust for her, as she becomes a newspaper columnist and writes about women's rights. The servants, too, continue to find themselves in dramatic situations: Bates goes to jail and is released; Thomas and Daisy crush on the same new servant; O'Brien is bitchy to everyone. The season ends with Mary giving birth to Matthew's child. They're one big happy family. Until Matthew dies suddenly in a car accident. Merry Christmas. Season four begins six months after Matthew's tragic crash. Mary, of course, is mourning her late husband, and to raise their child, George, as best she can. After realizing she's "spent too long in the land of the dead," she decides to pick herself up, and is ready to move on. As Matthew's widow, Robert informs her she owns half of Downton, and so she begins to involve herself in the financial goings-on of the estate. She has two new suitors — Lord Gillingham and Charles Blake. Edith becomes smitten with a married man, Gregson, and ends up having his child, but not before he flees the country, which results in Edith giving up her child, Marigold, to be raised by farmers. Downstairs, servants are affected by Matthew's death, as well. His valet, Molesley, takes a demotion to footman. Anna is raped, and Bates vows to avenge her. Curiously, Anna's rapist winds up dead, but the jury's still out on whether or not Bates killed him. Other servants crush on each other. Carson and Mrs. Hughes walk into the ocean. They hold hands. This is Downton's finest moment.

5) Whoa. That sounds ... dramatic.

Yes. This show is nothing if not deliciously contrived melodrama. It's maudlin, sentimental, and overwrought. Creator Julian Fellowes acknowledges this, explaining that his series is about "taking characters to the brink." Said Fellowes, "Downton deals in subjecting a couple of characters per series to a very difficult situation, and you get the emotions that come out of these traumas."

At Vanity Fair, David Kamp says the show's premise hinges upon "the grave consequences of the misdone thing."

If a raspberry-meringue pudding goes wrong — mistakenly finished with a sprinkle of salt rather than sugar — then the dinner guests must retch terribly and the cook must be sent down to London for risky cataract surgery. If the eldest and most eligible daughter in the house has a spontaneous fling with a handsome young Turkish diplomat, then she must suffer the horror of having him expire in her bed, leaving her to bear the burden of hushed-up scandal, a blot upon the family name, and, by dint of the damage she has done to her marriage prospects, the potential unraveling of the Crawley way of life as it has been known for generations.

The stakes are high, in other words, so high in fact that an action as seemingly unimportant as serving the Granthams dinner the way the Americans do it (ladies first!) could have devastating consequences for every single character on the show. Sure, a world in which gravy and etiquette are so highly esteemed is a distant world indeed — but that's the point.

Downton revels in a world we're not familiar with; a world where rich people aren't jerks, and poor people serve them with gladness and gratitude; where chastity is not only a virtue but a public duty; where a woman's integrity and a man's honor are worth as much as a 5,000-acre plot of land.

Of course some of these ideas sound absurdly outdated today, but that's part of the series' allure, argues James Parker. In a piece at The Atlantic, Parker considers why the series is just so popular:

Cultural amnesia? Falling standards? From Brideshead Revisited to this, in 30 years — what can it portend? Not much, is the answer. The British public is sentimental and nostalgic: it likes looking at sumptuous interiors, lavish costumes, and Dame Maggie Smith. From the manicured vistas of a country estate, it gets its little hit of arcadia. Downton Abbey is a harmless, anachronistic masque of manners, in which the players keep obediently to their roles and thereby gratify the innate conservatism of the audience.

6) Why does the show lose so many main characters?

Good question. In an interview with People, Fellowes said that when a character dies, "it is because the actor wanted to leave." Which means the absurd character deaths on Downton Abbey are not really the fault of the writers.

Since its debut, Downton has lost several beloved characters, most notably Sybil and Matthew. Both characters' deaths were written into the script when the actors portraying them refused to continue on the show. Unlike American television, where networks usually sign actors to deals that run five, six, or seven years, British series give their stars three-year contracts.

Dan Stevens's (Matthew) exit was undoubtedly the most devastating death thus far, as audiences watched his relationship with Mary grow for three years, only to be ended abruptly in a car crash. Stevens told The Telegraph that when his three-year option was coming to a close, he decided he wanted freedom to pursue other projects.

Jessica Brown Findlay, who played Sybil, also told The Telegraph she wanted to be free of Downton because she was worried of being pigeon-holed: "I didn't want to play Sybil for years and then discover it was the only thing I could do. That was a much more terrifying prospect than unemployment."

7) How have critics responded to the show?

When Downton first premiered, many US critics "swooned over it," says TV critic Alan Sepinwall.

However, as the New York Times noted in February 2012, more and more critics came to "torch" the show. Plenty of critics just had it with the crazy story turns and melodrama.

But one line of argument focused far more on the series' creator, who, according to James Fenton, is in a very similar inheritance situation to the Crawley family he writes about. That is, he "is married to someone who — were it not for the anomaly of our laws of primogeniture — would be in line to inherit the title of the present (presumably the last) Earl Kitchener of Khartoum." For Fenton, then, Downton Abbey is "brazenly promoting the class interests of its creator." The show, the argument goes, is an apologetic for the extremely wealthy. After all, Downton's aristocrats are portrayed very sympathetically.

Writing in Forbes, Jerry Bowyer challenges the claim that Downton Abbey is pushing any specific economic or political ideology, right or left:

Fellowes seems to be saying that the old order had its day; it was good, though not perfect, during its time. It deserves a decent burial and a fond memory. And he also seems to be saying that change for change's own sake is just as destructive as preservation for preservation's own sake.

8) But even if not all critics rave over it, the show has become something of a cult phenomenon, right?

Absolutely! There's no denying Downton's place in 21st-century pop culture. The show is enormously popular! There have been many spoofs and parodies, including this perfectly adorable Sesame Street spoof, called Upside Downton Abbey.

According to the Daily Beast, celebrities such as Katy Perry and Ru Paul have discussed their love for the period drama. Michelle Obama is a big fan, too. And the show is a hit not only in the UK and US, but also in Denmark, Netherlands, Italy, Australia, Norway, Belgium, Israel and Iceland, according to The Telegraph.

Bowyer thinks the show's popularity also shows that TV audiences want political and ideological diversity in their programming: "there is no inherent need for good TV to be left of center. Stories sympathetic to virtue, preservation of property, and admiration of nobility and of wealth can be told beautifully and to wide audiences."

David Kamp, for Vanity Fair, suggests a simple explanation for why we're so drawn to the series, in spite and perhaps because of its melodramatic flair:

The show is welcome counter-programming to the slow-burning despair and moral ambiguity of most quality drama on television right now. Mad Men, Breaking Bad, Homeland-all are about people who succumb to the darkest, most transgressive aspects of their nature. Downton Abbey, meanwhile, is largely about people trying to be ... good.

Correction and update: This piece has been corrected to say that Downton Abbey is produced by Carnival Films. A minor spoiler from an upcoming episode was also removed.