Pirate

A Pirate in the world of One Piece is anyone, who raises a Jolly Roger, whether they commit an act of Piracy or not. This is not, however, usually is not enough to give anyone a bounty but is enough to be arrested by the Marines. Mountain Bandits are said to be the opposite of Pirates and have not been known to get along with each other too well.

There are two types of Pirates in One Piece, but the terms were only in the original Romance Dawn chapter, and have not yet been mentioned in the current version of One Piece and it's doubtful they still apply to it.

Types of Pirates
In the two Romance Dawn one shots of One Piece the pirates are split into two groups: Peace Maine and Morgania. However these concepts are abandoned in One Piece itself, possibly due to the fact most pirates are a combination of both Peace Maine and Morgania ideals.

Peace Maine
Described in Romance Dawn Version 1, a Peace Maine is a Pirate who goes on adventures, and doesn't really care about personal treasures or going around fighting other Pirates. That is not to say that they will not steal treasure from others if it is there and the chance is open, but their primary goal is usually not to own it and greed is generally not their primary motivation. More often than not, a peace maine pirate sees his or her own crew as their most valuable treasure, and to them, not even the legendary treasure of One Piece can match the value of each and every crewmate.

Morgania
The Morgania fight for treasure and personal gain. They are greedy and love to fight just to cause other people pain and misery. In Romance Dawn Luffy disliked Morgania and only wanted to recruit Peace Maine Pirates.

The Four Blues
Generally outside of the Grand Line, most pirates are considerably weaker than those inside. Often, they are left untouched by the Marines because their attention is drawn towards the Grand Line rather then the East, West, North, or South Blue oceans.

That is not to say that they do not have their share of villainous pirates, as even in the weakest of the blues, the East Blue, powerful men like Don Krieg and Arlong were found. Generally, few people in the Four Blues have access to Devil Fruits or general knowledge of them. Most pirates seen before the Straw Hat Pirates entered the Grand Line fight by using of some form of weapon, the only exception being Buggy (whose Devil Fruit was found by the Jolly Roger Pirates, in the Grand Line).

The Grand Line
While there are individual pirate crews roaming the Grand Line, the more powerful pirates reside in this sea. These are namely the Shichibukai and the Yonkou.

Generally, the weaker pirates are often weeded out by the Marines or Shichibukai before they can get any further. The unfortunate ones don't even make it to their first island due to a lack of understanding on how the weather works on the Grand Line. The Grand Line is where you're most likely to see Devil Fruit users, both in and out of pirate crews.

In the second half of the Grand Line the most powerful pirates are the Yonkou. The second half of the grand Line (dubbed the "New World") is their playground and it forms a rather dangerously balanced part of the One Piece world.

The Pirate King
Pirate King (called King of the Pirates in the English versions) is the strongest pirate alive and owner of the legendary treasure that was later dubbed as "One Piece". "Kaizoku-Ō" (海賊王), the source of the term, literally means "Pirate King".

The English manga initially used "Pirate King" but later switched to "King of the Pirates". After "King of Pirates" became used in the manga, 4Kids chose to use "King of the Pirates" for the dub of One Piece.

The term "Pirate King" was originally simply a nickname for Gol D. Roger to distinguish himself among swashbucklers. Upon Roger's execution, the name was romanticized by the people of the One Piece world into an actual title, much in the same way One Piece itself was simply "Roger's treasure" until the Pirate King's death. In the English manga and anime, "Pirate King" clearly marks this distinguishment; although Gol D. Roger was Pirate King, Monkey D. Luffy seeks to become the new Pirate King 22 years later.

Before his death, Pirate King Gol D. Roger hid the One Piece. It was rumored to be located at Raftel, the island at the end of the Grand Line. The frenzy over discovering and owning such a massive treasure sparked the "Great Age of Pirates". Until One Piece has been claimed, there will be no current Pirate King.

Right now, the closest person to becoming the Pirate King is Whitebeard (Edward Newgate). However, many people who had met Luffy, such as Coby and Helmeppo, believe that he will be the Pirate King; Kokoro also addressed Luffy as the Pirate King himself and Shakuyaku has stated that both she and Silvers Rayleigh were rooting for Luffy to achieve this goal.

The reason for a person wanting to be be pirate king vary, people like Blackbeard and Gecko Moria wish to have it for the power and influence the title would come with, while others like the Yonkou are considered candidates for it because they're extremely powerful and very close to it, but the two shown so far appear not to have any interest in it. And still others like Luffy and Crocodile (prior to the event that caused him to let go of it) wish to become pirate king because it is a dream of theirs. Luffy (and Crocodile in his youth) seem to want for the adventures that are involved with becoming Pirate King. The Pirate King is said to be the ruler of the sea (Luffy awnsers this when he told Eneru he is going to the Pirate King and then Eneru ask him about the country the Pirate King rules, Eneru says then that would be a very interesting title).

Before the Golden Age
Pirates have long been a part of the way of life of the One Piece world. The oldest known group of pirates mentioned were the ones under Dorry and Brogy from more than 100 years ago. However, despite pirates existing back, none of them were noteworthy enough to shake the world.

Then all this changed with the arrival of the great Pirate Gold Roger. Roger set about doing what no one had done before - conquering the Grand Line. He succeeded and in doing so made his way to Raftel and left behind somewhere in the world, his most prized possession One Piece. Roger brought about an air of romance about being a pirate and upon his death his final words sent others to sea to become a pirate. Things would never be the same again.

The Golden Age of Pirating
The death of Roger sent many pirates to the Grand Line, hoping to find his treasure and become the Pirate King. However with the new wave of pirates came a new change that even Whitebeard noted.

Over the next few decades the old figures of the pre-pirate age began to disappear due to the span of time. This has left fewer and fewer people aware of the days of pirating before Roger's death. Many old values shared by the pirates of the pre-pirate age have slowly began to die. Even once commonly sung songs like Bink's sake have begun to fade out of memory, save from the minds of all but those who still remember the olden days of pirating (such as those like Brook and Shanks). Although newer pirates still adopt these values some completely go in a different direction, the most prominent is Doflamingo who speaks of a new age where pirates should stop dreaming.

With the Great Age of Piracy spiraling out of control, this has led to the World Government to become deeply concerned. In response, they created the Shichibukai and sent them out to kill other pirates. They also allowed themselves to easily be tricked by Spandam into a plan to gain Pluton, unaware that he had alternative motives in mind.

Coming of the New Age
In the current storyline, the new age is fast approaching. This new age of Piracy is being brought upon by changes in the world. Various characters who have mentioned it either speak of a world on the verge of chaos, or a great age where Pirates no longer chase their dreams.

Related to this incoming age in particular is the current capture of Whitebeard's second division captain Fire Fist Ace. This significant action has already seen the Shichibukai assemble together to enter a war against Whitebeard himself.