Almost all humans are born with five different senses. Your senses are basically defined as methods of perception. The five senses include smell, taste, touch, sight, and hearing. When all of the senses work together, they give people better perceptions, however there are some people that do not have all five of their senses. When someone is missing one of their senses, the ones that they do have become more perceptive and try to make up for the sense that does not work.
Your sense of smell is referred to as olfaction. A humans ability to smell is very important, an our olfactory system is able to differentiate between more than 10,000 different odors. Scientists have made great advances in figuring out how a humans sense of smell works. Every time you breathe, you inhale air into your nostrils, the air passes through your nasal cavity and into your olfactory system, which is packed with millions of receptor neurons. Every time you inhale, and air hits the receptor neurons, odor molecules are picked up by little hairs called cilia which are located on the neuron receptors. The receptors then send a signal to the brain, which is able to process what you are smelling, whether it be perfume, or cookies in the oven. There are a small percentage of people that have no sense of smell at all, and those people have a disorder called Anosmia. Anosmia generally results from damage to the olfactory senses.
Taste is another of the five senses, and is very much related to your sense of smell. We are able to taste with the use of taste buds which are located on the tongue. The taste buds along with taste receptor cells located in your mouth can distinguish between sweet, sour, salty, and bitter. People that suffer from Anosmia have a harder time tasting things because your sense of smell and taste are connected. Being able to smell an odor helps your taste buds to ultimately work better.