In the very beginning, the newborn universe was full of particles, but all of them were without mass, hurtling freely at the speed of light, much like photons of light. However, one trillionth of a second after the big bang, a field named after Peter Higgs switched on.
Particle physics' standard model implies that this "Higgs field", is comprised of "Higgs bosons" and permeates throughout space, interacting with particles with varying strengths. Some of the particles interact more strongly, therefore experiencing more resistance, and as such appear heavier.
In order to find the Higgs boson, protons are fired at each other at the speed of light with three-storey high detectors keeping a watchful eye over the proceedings. When the protons collide there is an extremely energetic flash, with the emmision of electrons, quarks and light. Occasionally, a Higgs boson may be seen. However, it is not that simple. Higgs bosons decay rapidly, making it exceptionally hard to find them.
These experiments were first conducted at the Large Electron Positron (LEP) machine at Cern, which ran between 1989-2000. The tests ran at the LEP effectively ruled out the existence of the Higgs boson up to a certain mass, while the Tevatron accelerator at Fermilab in Illinois, which ran up until 2011, searched for the particle above up to a mass of around 120 gigaelectronvolts (GeV).
Fast forward four years and the CMS research team has reported a Higgs-like particle with a mass of 125.3 GeV, while the Atlas team has reported a Higgs-like particle at 126.5 GeV. Both these results come with respective confidence of 4.9 and 5 sigma values. This essentially means that there is a 99.9999% chance that this isn't a statistical fluke.
Peter Higgs admitted:
I never expected this to happen in my lifetime and shall be asking my family to put some champagne in the fridge.
Cern hasn't officially claimed the definitive discovery of the Higgs boson, and there is still a doubt about whether this is the "Standard Model" Higgs that was first theorised, but whatever the outcome, there is still plenty more to be discovered!
Peter Higgs and Francois Englert, from Belgium, will share the 2013 Nobel Prize for Physics.