I decided to make a short summary about Hunter X Hunter Story Arcs.
This article contains SPOILERS so tread carefully!
Hunter Exam Arc
Number of episodes: 31 (1999 version) | 21 (2011 version)
Manga Chapters: 1~38
The very first arc of the Hunter X Hunter follows Gon when he meets a mysterious hunter who claims to know his father. He gave Gon a Hunter Card and thus starts Gon’s desire to be a hunter. While participating in the Hunter Exams, Gon met a lot of different people. Some became his friends while others became his rival. However towards the end of the exam, one of Gon’s friends, Killua has got himself disqualified, by brutally killing an exam participant, and is forced to go back to his home.
Zoldyck Family Arc
Number of Episodes: 5 (1999 version) | 5 (2011 version)
Manga Chapters: 39~43
The Zoldyck Family Arc takes place immediately after the Hunter Exam Arc after the incident that happened between Killua and his brother, Illumi. Gon, Kurapica, and Leorio decided to go to Killua's home into the Kukuroo Mountain. However, the trio quickly realized how different the World Killua grew up in.
Heaven's Arena Arc
Number of Episodes: 8 (1999 version) | 10 (2011 version)
Manga Chapters: 44~63
After taking back Killua, the four friends decided to go on their separate ways, in order to pursue each and their own goals. Kurapica left to go and try to take a bodyguard job, while Leorio continued on and pursue Medical Studies to become a doctor. Gon and Killua decided to stay together and participate in the one of the most famous fighting tournament in the world, that takes place in high tower called, The Heaven's Arena. During their time in the tower, the duo learned of a mysterious power called Nen.
Yorknew City Arc
Number of Episodes: 26 (1999 version) | 22 (2011 version)
Manga Chapters: 64~119
As they leave the Heaven's Arena, Gon invited Killua back to his hometown for a vacation. Here, the duo discovered a mysterious game called Greed Island that was created by a group of powerful nen user, one of which is none other than Gon's father, Ging Freecs. Meanwhile after his own intense Nen training, Kurapica decided to take a job as a body for the Nostrad family, with the desire to track down and retrieve the stolen eyes of his tribe. Little did they know, the four will have an unplanned reunion in the city of Yorknew. And in this city, they will encounter the source of Kurapica’s hatred, the infamous thieves called the Phantom Troupe.
Greed Island Arc
Number of Episodes: 22 ( 1999 version) | 17 (2011) version
Manga Chapters: 120~185
After helping Kurapika with his fight against the Genei Ryodan, the four again decided to go on their separate ways. Leorio goes back to his medical studies, Kurapica resumes his job for the Nostrad family while Gon and Killua continues their pursuit to get a Greed Island game. Gon and Killua eventually found someone to sponsor them and they finally got to participate in Greed Island. Inside the game, Gon and Killua meet a very strong nen user, called Biscuit Krueger, and trained under her. As the story progresses, the trio discovers a mysterious player called Bomber who had killed a lot of Greed Island players. The trio then decided to team up with other Greed Island players to defeat the mysterious Bomber. Unbeknowist to them, the Phantom Troupe has also find their way inside the game with the quest to find a Nen-Remover to help their fallen leader.
Chimera Ant Arc
Number of Episodes: 61 (2011 version only)
Manga Chapters: 186~318
This arc starts immediately after Gon was tricked by Ging. Instead of meeting his father, Gon and Killua met Kite. Soon after their meet, the trio was hired to go to an island, called the NGL, in order to investigate the mysterious creatures that roams and kills the island's inhabitants. Soon, the majority of the islands population is wiped out and turned into chimera ants. The Hunter Committee then decided to send more Hunters to eliminate the Chimera Ant threat.
13th Hunter Chairman Election Arc
Number of Episodes: 11 (2011 version only)
Manga Chapters: 319 ~
Gon is left in a dangerous state after his intense battle against the Chimera Ants. Killua, with his desire to help his friend, decided to go back home to find a way to cure Gon. Meanwhile, following the will of the late Hunter Chairman, Isaac Netero, his 12 most trusted followers, the Zodiac, has conducted the 13th Hunter Association Chairman election.
Dark Continent Arc
MANGA ONLY ~ Currently on HIATUS
The arc primarily revolves around Ging Freecs, Kurapica, Leorio and the Zodiacs. Two group starts an expedition into the mysterious place called The Dark Continent.