Dota 2 is a multiplayer online battle arena (MOBA) video game developed by Valve Corporation, which released in 2013. In it, two teams of five players compete by selecting pre-designed in-game hero characters, each with a variety of innate skills and deploy-able powers, and cooperating together to destroy the base of the other team before their own base is destroyed as to win the round. The game is played from a top-down perspective, and the player sees a segment of the game's map near their character as well as mini-map that shows their allies as well as any enemies revealed outside the fog of war. The game's map has three symmetric "lanes" between each base, with a number of automated defense turrets protecting each side. Periodically, the team's base will spawn an army of weak non-playable minions that will march down one lane towards the opponents' base, fighting any enemy hero, minion, or structure they encounter. If a hero character is killed, that character will respawn back at their base after a delay period, which gets progressively longer the farther into the match.
As with previous years of the tournament, a corresponding battle pass for Dota 2 was released in May 2017, allowing the prize pool to be crowdfunded by players of the game. Known as the "Compendium", 25% of revenue made by it was sent directly towards the tournament's prize pool. At the time of event, Dota 2 featured 113 playable characters, called "heroes". Prior to each game in the tournament, a pre-game draft was held between the opposing team captains to select which heroes their teams will use, going back and forth until each side has selected and banned five heroes. Once a hero is picked, it cannot be selected by any other player that match, so teams use the draft to strategically plan ahead and deny the opponent's heroes that may be good counters or would be able to take advantage of weaknesses to their current lineup. The first pick in a match is decided by an in-game coin toss, and switches between each game in that match; the team that does not get first pick does get the option of which side of the map to defend.
The tournament initially began with the Commonwealth of Independent States (CIS), China, Europe, North America, South America, and Southeast Asia online regional qualifiers in June 2017. Following that, two separate best-of-two round robin groups consisting of nine teams each were played from August 2–5, with lowest placed team from both being eliminated from the competition. The remaining 16 teams moved on to the double elimination main event at the KeyArena in Seattle from August 7–12, with the top four finishing teams from both groups advancing to the upper bracket, and the bottom four advancing to the lower bracket. The first round of the lower bracket was treated as single-elimination, with the loser of each match being immediately eliminated from the tournament. Every other round of both brackets was played in a best-of-three series, with the exception being the Grand Finals, which was played between the winners of the upper and lower brackets in a best-of-five series.
Six teams were invited directly to the event, with an additional twelve qualifying teams participating. New to the event from previous years was the expansion from 16 to 18 total teams, as well as establishment of new qualifying regions; the Americas were split into separate North and South America regions, and the Commonwealth of Independent States (CIS) region was split off from Europe. The International 2016 champion Wings Gaming disbanded earlier in 2017 with its members taking a break from professional Dota, marking the first time in the International's history that a defending champion or any player of its former roster did not defend their title. The rosters of two independent teams, Planet Dog and Team NP, were signed after the qualifier stage respectively by the eSports organizations HellRaisers and Cloud9. Valve tournament rules allow for players to freely play for another organization without restrictions, as long as the rosters remain the same.
As with previous years of the event, Seattle KCPQ reporter Kaci Aitchison reprised her role as co-host and interviewer. However, Paul "ReDeYe" Chaloner, the desk host of the last two Internationals, was not invited. Instead, Counter-Strike: Global Offensive tournament host Alex "Machine" Richardson and StarCraft personality Sean "Day" Plott replaced him.