how was it discovered?
he first evidence of helium was observed on August 18, 1868, as a bright yellow line with a wavelength of 587.49 nanometers in the spectrum of the chromosphere of the Sun.
Helium
The first evidence of helium was observed on August 18, 1868, as a bright yellow line with a wavelength of 587.49 nanometers in the spectrum of the chromosphere of the Sun. 
where does the world's helium come from Most helium on Earth is a result of radioactive decay and is found in large amounts in minerals of uranium and thorium, including uraninite. how is it extracted? UNANSWERABLE does it have any uses? Yes, commercial, recreational, scientific as well as medical use. what are its commercial use? One of its commercial use is that its mixtures such as trimix, heliox and heliair are used for deep diving to reduce the effects of narcosis, which worsen with increasing depth. what are the characteristics of it? In the perspective of quantum mechanics, helium is the second simplest atom to model, following the hydrogen atom.
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Helium [SEP] Scientific discoveries
The first evidence of helium was observed on August 18, 1868, as a bright yellow line with a wavelength of 587.49 nanometers in the spectrum of the chromosphere of the Sun. The line was detected by French astronomer Jules Janssen during a total solar eclipse in Guntur, India. This line was initially assumed to be sodium. On October 20 of the same year, English astronomer, Norman Lockyer, observed a yellow line in the solar spectrum, which, he named the D because it was near the known D and D Fraunhofer line lines of sodium. He concluded that it was caused by an element in the Sun unknown on Earth.