Dark clouds of cold gas are found throughout our Universe. Many are oddly spectacular appearing in sharp contrast to the brilliant stars.
Gas Pillars in the Eagle Nebula (M16): Pillars of Creation in a Star-Forming Region
Source: NASA, ESA, STScI, J. Hester and P. Scowen (Arizona State University)
The process of star birth begins with a nearby explosion (most likely the death of a massive star in a supernova), that sends ripples through the gas cloud. Small clumps start to form and as the clumps grow their gravity increases so that more matter is attracted and they grow even bigger.
As gravity pulls the mass inwards, the centre of each clump heats up. When the core reaches a temperature of a few million degrees, hydrogen atoms begin to fuse together to form helium. This process is called nuclear fusion and is the reaction which powers a hydrogen bomb.
When the nuclear reactions begin, the clump of gas is now a star. The nuclear reactions give the star energy to make it shine and to counteract the inward pull of gravity. Young stars light up the gas still surrounding them which produces the beautiful nebulae.