What is formed in H II areas?

HII region is typically a cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light years. H II regions may give birth to thousands of stars over a period of several million years. The Orion Nebula, now known to be an H II region, was observed in 1610 by Nicolas de Peiresc by telescope, the first such object discovered.