HBO’s Game of Thrones has been a TV game-changer.

Taking an epic fantasy book series and transforming it from a cult hit into the most talked about drama in the world, the show has pushed the boundaries on what can be achieved on the small screen.

[Read more: The 10 most shocking moments in Game of Thrones]

But what about all the TV viewers who are still lagging when it comes to knowing their Dothraki from their Daenerys?

Game of Thrones seasons 1-7 are available to buy now on the BT TV Store and here is our quick beginner’s guide for anyone preparing to walk into the world of Westeros.

1. Know your Houses

There are four major families, often referred to as Houses, that run through the story, together with a large number of ancillary clans and, servants and general hangers-on. There’s also the Night’s Watch, a sort of ‘Foreign Legion’ of disgraced aristocrats and low-born criminals charged with garrisoning a defensive wall - The Wall - against the unspeakable horrors of the far north.

The Starks

The first family we meet are the Starks. They’re a fundamentally decent bunch, led by gruff, inflexible Ned (Sean Bean). Their ancestral home is the most northerly of the great houses, and nearest to The Wall.

Ned’s wife is Catelyn, descended from House Tully. She has two daughters: Sansa, a diffident girl who resembles her quite closely, and Arya, something of a tomboy.

Ned and Catelyn also have three sons: Rob, a fine swordsman and a natural leader, Bran, an adventurous lad who’s always getting into scrapes, and Rickon, who is frankly quiet enough that you don’t need to worry about him all that much.

Also living with the Starks are Jon Snow, widely believed to be the bastard son of Ned and an unknown mother, and Theon Greyjoy, who is technically a hostage but is treated almost as a family member by the fair-minded Starks.

The Lannisters

Wealthy, haughty and proud, the Lannisters are still based at their family seat of Casterly Rock, where a sizeable gold-mine bolsters their fortunes, but three key members of the family are currently living in King’s landing, the capital city of Westeros.

As the series opens Cersei (Lena Headey) is married to current king Robert Baratheon. Her twin brother Jaime, with whom she has a secret incestuous relationship, is one of the king’s bodyguards – despite having assassinated the previous king, Aegon Targaryen.

The third, and frankly best, of the Lannisters is Tyrion (played by Peter Dinklage). A dwarf, he is despised by his father and hated by his sister although he has a pretty cordial relationship with brother Jaime. He’s often underestimated because of his stature but he’s one of the wisest as well as the wittiest of all the characters in the show.

The Baratheons

Robert Baratheon (Mark Addy) is the current ruler of The Seven Kingdoms – the confederation of nations south of The Wall. He’s comparatively new to the job, having ousted previous king Aegon not long before the series opens. He’s fat, jolly, likes drinking and hunting and is seemingly oblivious to the fact that his children resemble his wife and her brother far more than they do him.
Robert has two brothers; Stannis, a dour sort devoted to the religious cult of The Lord of Light, and Renly – a freewheeling, charismatic sort who hides his sexuality from his family.

The Targaryens

Game of Thrones

The Targaryens were the royal family of Westeros until supplanted by the Baratheons a few years before the series opens. While they once owned and trained fearsome dragons and had some sort of magical immunity to fire, their glory days are far behind them.

Two surviving members of the family, Viserys and his younger sister Daenerys, have been smuggled out of Westeros by Targaryen loyalists. They soon fall in with the brutish Dothraki, a nomadic warrior horde who seem to care about little other than combat and equestrianism.

Viserys plots to return to Westeros and reclaim the throne, but his younger sister is the one to watch here. Daenerys, played by Emilia Clarke, is one of the key characters of the series.

2. Characters you love will get killed

Warning: Don’t become too attached to any of the characters in Game of Thrones, because original author George RR Martin is fond of a brutal and heartbreaking death.

That doesn’t mean everyone gets killed off one-by-one - in fact there are some surprising survivors still going strong in season 7 – but we’d still advise you to brace yourself for some jaw-dropping moments.

3. Don’t worry about spoilers

Did someone at work reveal that ‘X’ died in season 2? Have you already heard everything about the infamous Red Wedding episode?

Don’t be put off by these spoilers. Not only is Game of Thrones filled with surprise twists and turns  in every single episode, the show is a so intricately plotted and epic in scale that even if you know a little about what’s going to happen, the show still packs a powerful and emotional punch.

And even if you’ve read the books, you can still expect a few surprises as the show takes a few detours from George RR Martin’s source material.

4. The incredible cast keeps getting better and better

From the very first season with Sean Bean, Peter Dinklage, Lena Headey, Michelle Fairley and Aiden Gillen, Game of Thrones has always had an incredible roll call of talent.

The show has also helped turn young actors Kit Harington, Emilia Clarke, Maisie Williams and Sophie Turner into Hollywood A-listers.

With every new season comes yet more incredible talent as Iwan Rheon, Diana Rigg, Mark Gatiss and most recently Jim Broadbent added to the cast

5. What's all this talk about how 'Winter is Coming?'

The seasons of Westeros are variable, with decades-long balmy summers giving way to equally lengthy ice ages. You’ll often hear characters – especially Sean Bean’s Ned Stark – mournfully say ‘Winter is coming’.

It’s not just because the Westerosi are worried about their heating bills. Winter is the time of The Others, when the mysterious blue-eyed creatures of the frozen north can lead their vast legions of reanimated corpses deep into human territory.

With that kind of danger imminent, the worst thing that the Westerosi could do would be to distract themselves with a bloody and divisive battle for the royal succession. Guess what they’re doing?

Game of Thrones S7 is now available to buy in the BT TV Store.

Seasons 1-6 are also available to own.

Press the BT Player button on your remote control, scroll across to Box Sets and browse now. Alternatively, press the blue button to search for the TV box set you want.

[Read more: The best new films on BT TV Store this month]