Game of Thrones is an American fantasy drama television series produced by the HBO cable network. It is based on the novel series A Song of Ice and Fire, written by George R.R. Martin, who serves as a producer, creative consultant and scriptwriter on the television series. David Benioff and D.B. Weiss created the television series and serve as executive producers, showrunners and the main writers.

To date, the series consists of seven fully transmitted seasons, comprising sixty-seven episodes in total, while the series is currently in post-production for its eighth and final season, which will consist of six episodes.

Production of the series is based in Belfast, Northern Ireland, mainly at the Paint Hall Studios. It is the largest and most expensive television production ever mounted in Northern Ireland. Filming for the series has also been conducted in Malta, Iceland, Croatia, Morocco, Spain, and the USA.

Adaptation process and catching up with the books
Seasons 1-4: A Game of Thrones, A Clash of Kings & A Storm of Swords
As of 2016, five books have been published in the A Song of Ice and Fire series, and author George R.R. Martin has predicted that there will be two more (though he is struggling not to let the final book run long, in which case it would have to be split, for a total of eight books).

The third novel, A Storm of Swords, was so long that it pushed the limits of how large a published book could physically be without pages falling out. Because the third novel was so long, the production team realized it would be impossible to condense it all into a single season, so the decision was made to adapt its contents across two seasons. While Season 3 ends with the Red Wedding, this actually happened in the middle of the third novel (similar to how Renly Baratheon suddenly died in the middle of Season 2). Jon Snow returned to Castle Black by the middle of the third novel. Daenerys Targaryen had not yet reached Meereen by the middle of the third novel. A few characters did advance further than this in Season 3, i.e. Bran Stark actually passed north of the Wall at the end of the third novel (he had so few chapters in the entire book that the TV producers didn’t want to space it out for two full seasons). By the end of the fourth season, most of the characters had completed their story from the third novel.

Season 5 and 6: Intercutting A Feast for Crows & A Dance with Dragons
What was originally planned as the fourth novel was even longer than the third novel, so Martin split it into two novels: A Feast for Crows (the fourth book) and A Dance with Dragons (the fifth book). The fourth and fifth books occur during a simultaneous timeframe: all of the chapters set in the Seven Kingdoms were moved to the fourth book, while all chapters set outside of the Seven Kingdoms (at the Wall or across the Narrow Sea in Essos) were moved to the fifth book. Though of course, despite splitting them because as one book they would have been longer than the third novel, Martin kept making additions to the fourth and fifth novels during the writing process, so both are nearly as long as the third novel.

It would be odd to spend an entire season with one set of characters while the rest do not appear, then reverse this in the subsequent season. So Seasons 5 chronologically presented events in the order that they happened. This is comparable to how J.R.R. Tolkien’s The Two Towers actually consisted of two halves: the first half entirely follows Aragorn since the end of the first novel, then the second half backs up in time to follow only Frodo’s perspective, but during the same timeframe since the end of the first novel. Peter Jackson’s movie adaptation, however, chose to simply intercut between the two storylines to show events in the chronological order in which they occurred. Thus “Season 5” consisted of the majority of the material from A Feast for Crows and A Dance with Dragons.

Seasons 7 and 8: Beyond the books
Given that there are currently five novels (with the third split into two seasons), but given the fact that the majority of the fourth and fifth novels have been adapted in season 5 and 6, there was only a very limited amount of material left to be adapted. Even so, Martin has told producers Benioff & Weiss the general outline of how the final two books are going to progress (so if a bolt of lightning strikes Martin, they’d still be able to finish according to Martin’s general plan).