Helium is obtained through natural gas as it is extracted from the ground. The helium is a result of the decay of thorium and uranium. As these elements decay, they release an alpha particle. That alpha particle is the nucleus of a helium atom.
Helium is a noble gas, which means it normally doesn't react with any other element. It is odorless, colorless and non-toxic, though inhalation of helium can lead to suffocation. This is why helium tanks for party balloons come with a bit of oxygen added.
Helium is used to cool superconducting magnets that are used in MRI machines and to help create the crystals that produce silicon chips. As of 2014, scientists are studying its properties as a superfluid because it remains a liquid even at temperatures near absolute zero. It is also used to cool nuclear reactors, and it helps protect arc welding. It's also used in cryogenics.
Although it's rare on Earth, helium is the second most abundant gas in the universe. It occurs in abundance in main sequence stars that are still converting their hydrogen into helium. It's also part of the atmospheres of the gas-giant and ice-giant planets, such as Jupiter, Saturn, Uranus and Neptune.