Symmetrical or all-out?

Since the advent of chess, it has been generally acknowledged that black has a one move disadvantage. This hardly means anything, but white does have a perceptible advantage in development. This is why the move e5, though solid, has lost some of its original popularity. A new move, a flank move, has gained popularity and it is c5. C5 serves a number of purposes. The most important is controlling the d4 square and preventing white from taking control. The move also restricts white from attacking too much, due to the dangers posed by the queen and the dark squared bishop along the g7-a1 and b6-g1 diagonals. If the queen moves to b6 quickly, then white's bishop cannot develop due to the hanging b2 pawn. The rook operates well for black along the semi open c-file. This well known opening is called the Sicilian defense. However, it has its shortcomings. It is a complicated opening to play as it has over a 100 variations and lines and hence isn't suited for blitz games where calculation has to be done quickly. It has also been described as being to passive and cramped. Thus it gives rise to many complex positions. If played correctly though, it favors black in the endgame due  to the center pawns. E5 is still considered to be very solid and forceful due to variations like the Berlin defense, which prevents white from pushing forward. What players choose it up to them, but both represent good ways of fighting back. Don't be misleaded though, defenses like Alekhine's defense (the Brooklyn variation) actually gives white extra moves to play with, but grants no significant advantage.

 Dragon variation