What are the main determinants of demand elasticity? Explain their importance

First is the nature of the good. Necessities have less-elastic demand than do luxury goods. Second, there's availability of close substitutes. The more substitutes exist and the closer they are to the original good, the more elastic demand will be. Third is the fraction of income absorbed; the smaller the fraction of income spent on an item, the more elastic demand will be. Fourth is the passage of time; the more time that passes after a price change, the greater the demand elasticity.