
Akatsuki (暁; Literally meaning "Dawn" or "Daybreak") is a  criminal organization of 
S-class missing nin  and is the most wanted group in all of the shinobi world. Their main  goal is to collect all of the tailed beasts for their plan of world domination. As such, Akatsuki,  despite initially having a minor role during Part I, have become the  primary antagonists in Part II. 
Akatsuki at any given time is composed of no more than ten  primary members, all of whom were S-Class criminals of their own  respective villages. Members always work in teams of two with the  exception of Zetsu, who functions as the organization's spy, and make  use of their unique skills to the team's advantage. Team members must  function very well or at least to accomplish their task even though they  have a mutual problems with each other. The organization is rarely  fully assembled, as seen in the end of Part I, when one member said it  was the first time in seven years when they were all together. 
Akatsuki is widespread, spanning several countries with agents in  various places. When one team finds a tailed beast and has to begin the  job of sealing the beast, they have hidden hideouts with many traps  ready, to do the three day log jutsu.
MAIN GOAL
Although some members joined Akatsuki to further their own goals, all  are united in Akatsuki's ultimate goal of gaining world domination.Nagato has mentioned a three-step process to work their way towards  this goal.First, they plan to obtain a large amount of money to support their  organization.Second, they plan to set up a mercenary group loyal only to Akatsuki.To build their reputation, they plan to accept any mission below the  usual cost and operate off of the excess funds earned in the first part  of their plan.Because there haven't been any wars in some time, the established  shinobi villages couldn't afford to charge such low prices, leading the  smaller countries to hire Akatsuki over the more expensive shinobi  villages.By using the tailed beasts, Akatsuki would start wars and then  immediately quell them, solidifying their reputation and convincing  every country to depend on them, thus cornering the market in shinobi  labor.Without any business, the other shinobi villages would collapse due to  the lack of funds.Finally, after Akatsuki is the only major force of shinobi in  existence, they can easily conquer the other countries.Members do not automatically learn of the plan upon joining; Hidan  didn't find out about it until he had been a member for quite some time.
The tailed beasts , nine gigantic demons of immense  power, are the main focus of much of Akatsuki's efforts and screen time  within the series. Each member is assigned to capture one of the nine  beasts alive or, in most cases, the person that beast has been sealed  into.Akatsuki has sealed seven of the nine beasts before the start of the Fourth Great Shinobi War.
MEMBERS
Pein
Uchiha Madara
Sasori
Deidara
Hidan
Kakuzu
Uchiha Itachi
Zetsu
Konan
Kisame