The opening is the first phase of the game and in which both players develop their pieces and engage them in battle.
A harmonious developing of the pieces in this phase of the game will lead to a good game for you further on. This is why you should be familiar with the basic concepts that rule the game and the ideas behind the openings.
Even from the 15th century a series of openings have been studied like : The Spanish game, The bishop's Opening, The French Defense, mostly opened and semiopened games. With time closed and semiclosed openings started to by analyzed. This kind of openings lead to a positional game and at least some notions of strategy were required in order to play the game. This days there are many books and publications written solely on this subject.
If you are a beginner it's a good idea to start out with learning just a few openings. It's also a good idea if those openings lead to opened and semiopened games; while playing this kind of games you will be able to develop your tactical sense. You should start studying closed and semiclosed games after you have learned a few notions of strategy.
The main idea behind all openings is to develop your pieces as harmonious and as fastest as possible and in the same time to disturb your opponent's positional development.
There are a few general rules you should follow when developing your pieces: