T H E   P R I M E  D I R E C T I V E 
(or General Order Number One):

The Prime Directive forms part of the governing law of the United Federation of Planets, including Starfleet.
It forbids interfering with the natural growth of less-developed civilizations.
The Federation Council first passed a series of executive orders. These General Orders provide specific directions to Starfleet vessels operating without immediate communication with Starfleet Command.
The General orders include the following:

General Order Number One:
Forbids anyone from interfering with the natural growth of less-developed alien civilizations.

General Order Number Six:
A ship's self destruct sequence must automatically activate twenty-four hours after the entire crew has died.

General Order Number Seven:
No vessel, under any circumstances, may approach Talo IV, and any vessel that does so, will be destroyed.(Don't ask me why..)

General Order Number Twenty-four:
A world must be destroyed if the galaxy is threatened by it.

Six of these orders form the basis of the Prime Directive.
When a ship loses contact with Starfleet, its captain acts as ambassador and military commander. He/She makes decisions on behalf of the Federation.
The Prime Directive and general orders establish strict guidelines for relations with alien cultures.
It raises as many questions as it answers. It can provide protection to less- developed cultures or be abused as a shield to hide behind to avoid making difficult moral decisions.

History of the Prime Directive:

The original Trek introduced the Prime Directive, but it has grown more important in the more settled twenty-forth-century(TNG, DS9,Voy).
It has become  a key guide to decision making.
    If Kirk often ignored the Prime Directive, Picard and Sisko cannot. Voyager offers an interesting situation, since it is lost in the Delta Quadrant and cut off from Starfleet. Janeway is the first Starfleet captain with a freer hand than Kirk.
    The Prime Directive grew out of errors committed by Federation citizens against newly met alien civilizations.
It commands that a society must be sufficiently advanced to prevent disruption before contact can be made.
    But it isn't simple.
Starfleet inevitably commands personnel to watch threatened worlds, and their inhabitants die without them being able to interfere.
    Strict interpreters of the Directive insist that this compiles with the natural law of governing the universe. 
More liberal ones say that circumstances can overrule the Directive.
Others insist that Starfleet has no right to judge which civilizations are worthy of survival.
Loose constructionists  accuse their opponents of hiding behind the Prime Directive to avoid making difficult morale choices.
Most often, those who work aboard starships in direct personal contact with alien worlds become loose constructionists.