The Large Hadron Collider (LHC) is the world's largest particle accelerator in the world's biggest particle physics lab, CERN. It caused quite a stir in its early years due to conspiracy theorists fearing that the experiment would create black holes or open the gates of hell. Almost 10 years since then, many, outside the scientific community had forgotten about the experiment and its purpose. As a science student majoring in physics, I'm obliged to inform the readers about the purpose behind performing such behemoth of an experiment. Spoilers: it is solely due to curiosity.
The idea that matter is made up of tiny units isn't quite modern. It was prevalent in ancient Indian and Greek civilizations. It was believed that atoms couldn't be split into smaller units so the curiosity about them ended there. The late 19th century had seen a boom in physical and chemical sciences due to the discovery of electron. This discovery helped us understand the interactions between atoms and most importantly, it showed that atoms can be split further. This re-ignited the curiosity to know whats in the smallest of particles and how they interact with each other. This marked the birth of Particle Physics. Since then, many sub-atomic particles had been discovered and the nature of once magical phenomena like electricity and magnetism, had been found.
Early days of particle physics didn't need big labs as the scientists probed the innards of atoms using indirect techniques like hitting them with other particles to see them interact. They observed these interactions, guessed the properties of sub-atomic particles and called them protons and neutrons. But the thirst for knowledge about the sub-atomic world wasn't quenched. They couldn't probe these particles as they're quite small and finally needed to break these particles to look what's inside them. So the particle accelerators were made. These accelerators accelerate sub-atomic particles to high speeds and make them collide so that they break into even smaller particles. This led to the discovery of quarks and gluons, the constituents of both protons and neutrons. Many particles are also formed in these accelerators just like during the creation (The Big Bang). Most of these particles are short lived outside the atoms. i.e. they combine with others or die off to form new particles. But they can 'live' long enough for us to study if we move them at high speeds. The shorter the particle's lifetime, higher the energy required to study it. So a bigger and powerful accelerator called the LHC was built.
Around the LHC, four main detectors were fitted at different regions. These detectors look at the particles when they collide and the scientists study their properties by performing analysis. A new particle is confirmed as a discovery only if the detectors detect the same particle independently. This eliminates the possibility of false discoveries. A recent discovery was the Higgs boson, the particle that gives mass to everything in this universe.
Though these discoveries doesn't contribute to the society rather than adding a few more pages in the text books. But we still do it so that we can have a better understanding of our universe and our purpose here. To physicists this is just like opening a present to find what's inside it.