Individual Demand means the goods and services demanded by an individual. Individual demand for a particular good means the demand for that good by a specific individual.
Individual demand curve is a graphical representation of corresponding quantities demanded by an individual of a specific good at different price levels. It is the locus of all the points showing various quantities of a commodity that a consumer is willing to buy at various levels of price, during a given period of time, assuming no change in the conditions/determinants of demand.
In a market there will be many individuals who demand for the product. Therefore, the market demand will be the total quantity demanded by all the individuals for that particular product. For example, if the market has only Individual A and Individual B who demand for a particular product, look at the following demand schedules and the demand curves.
As we can see, the market demand curve is flatter than the individual demand curves. This actually means it is more elastic. For the market as a whole, the percentage change in quantity demanded will be bigger than the percentage change in price, as compared to that of individual demand curves.