Explanation:

A buying process is the series of steps that a consumer will take to make a purchasing decision. A standard model of consumer purchase decision-making includes recognition of needs and wants, information search, evaluation of choices, purchase, and post-purchase evaluation.
You can't make a purchase decision unless you actually know what you want or need. A need is an essential product or characteristic of a product that you must obtain. For example, you need water to survive. A want, on the other hand, is some product or product characteristic that you desire but is not essential. For example, while you may want to quench your thirst with soda, you don't need it - water will suffice.

Needs often arise because of problems, such as breaking the cell phone you use for business. Wants may arise as part of your need for a product, or because you have been influenced to want a product because of some outside influence, such as advertising or observing someone enjoying it. For example, you may need a new cell phone, but after watching countless colleagues use their smartphones, you really want to upgrade to a smartphone.