Scientists had been chasing the Higgs boson, nicknamed the 'God particle' for more than four decades.
In July the team from the European nuclear research facility at CERN in Geneva announced the detection of a particle that fitted the description of the elusive Higgs.
The boson is believed to give matter mass via an associated 'Higgs field' that permeates space. Without the property of mass, the universe we live in could not exist.
Scientists used the world's biggest atom smashing machine, the Large Hadron Collider on the Swiss-French border, to track down the missing particle.
Finding the Higgs topped the list of most important discoveries of 2012 released by Science, a prestigious scientific journal, the 'Daily Mail' reported.
"Mass must somehow emerge from interactions of the otherwise mass-less particles themselves. That's where the Higgs comes in," Science news journalist Adrian Cho, who wrote about the discovery in the journal's latest issue, said.
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Nine other pioneering achievements from 2012 which made it to the list included sequencing of the DNA blueprint of the Denisovans, an extinct species of human that lived alongside Neanderthals and the ancestors of people living today.
Japanese researchers showing that embryonic stem cells from mice could be coaxed into becoming viable egg cells was hailed as another breakthrough.
Curiosity rover's Landing System was also an achievement for the scientific world as mission engineers at the American space agency NASA safely and precisely placed the Curiosity rover on the surface of Mars.
In another advance, researchers used an X-ray laser, which shines a billion times brighter than traditional synchrotron sources, to determine the structure of an enzyme required by the parasite that causes African sleeping sickness.
In 2012, scientists using a tool known as TALENs, which stands for 'transcription activator-like effector nucleases', altered or inactivated specific genes in animals such as zebra fish and toads, and cells from patients with disease.
A team from Netherlands gave solid evidence of the existence of Majorana fermions, particles that act as their own antimatter and annihilate themselves.
A decade-long study reported this year revealed that the human genetic code is more functional than researchers had believed while another team showed that paralysed human patients could move a mechanical arm with their minds and perform complex movements in three dimensions.
Researchers working on the Daya Bay Reactor Neutrino Experiment in China found the last part of the jigsaw describing how particles known as neutrinos morph from one strain or 'flavour' to another travelling at near-light speed.