What are asteroids and how ESA is tracking them?

tech.hindustantimes.com:

The existence of asteroids has been a big concern for Earth and Scientists from all over the world try to track these rocky objects moving around the Sun. According to scientists, there can be possible threats to Earth from asteroids and that is why they should be tracked by us.

Asteroids are celestial bodies composed of rocky materials that have survived since the solar system's formation about 4.6 billion years ago. According to NASA, most of these asteroids come from the main asteroid belt, situated between Mars and Jupiter. Currently, NASA has identified over 1 million asteroids. These space objects follow elliptical orbits around the sun, and due to their irregular shapes, they often tumble and rotate unpredictably as they traverse through space. According to the European Space Agency, Asteroids are old rocks from the early days of our Solar System. Some of them might have brought complex molecules and possibly early life to Earth billions of years ago.The Chicxulub asteroid is very famous. It hit Earth 66 million years ago and caused a mass extinction event, wiping out many species, including most non-flying dinosaurs.Big asteroid impacts are very rare, but smaller ones are more common. They can still cause serious damage, like the one in 2013 that caused the Chelyabinsk event. Sometimes these asteroids reach the ground, but even if they break up in the atmosphere, they can create powerful explosions, shattering glass, damaging buildings, and hurting people nearby.

A "near-Earth object" (NEO) is any natural object, like an asteroid, that comes close to Earth in its orbit. We know of more than 600,000 asteroids in our Solar System, and about 20,000 of them are near-Earth objects. About 800 of those are on ESA's risk