The factors causing an increase in demand of a commodity are:
(i) Favourable Change in Tastes and Preferences: Tastes and preferences of the consumers are influenced by advertisement, change in fashion, climate, etc. Other things being equal, demand for those goods increases for which consumers develop tastes and preferences.
(ii) Consumers Expectations: If the consumer expects a significant change in the availability of the concerned commodity in the near future, he may decide to change his present demand for the commodity. Particularly, if the consumer fears acute shortage of the commodity in the near future, he may raise his present demand for the commodity at its existing price.