 In this module, and next several modules, we will talk about genetics. Genetics is a branch of biology in which we study the modes of inheritance, how genetic information is passed from one generation to next. Before we jump into the subject, I would like to give you a brief historic perspective. It had been long recognized that children inherit features from their parents. Humans were breeding plants and animals 5,000 years ago. These people recognized the genetic information is passed from one generation to next. Children offspring take features and characters from their parents. The prevailing view of hereditary was blending, which basically implies that genetic information, once it is passed on to the next generation, it does not separate. I'll give you an example of the principle. For example, we mix two dyes, blue and red. We will get purple dye. Once we have formed the purple dye, we cannot take out red or blue color from this purple dye. Mendel did a lot of experiments. This is a gentleman who basically gave birth to this branch of biology, genetics. Mendel did some experiments which proved that the principle of blending is not valid. It is a particulate principle that is valid. For example, let me tell you, explain it to you in terms of our example, the purple dye. If purple dye, for the sake of explanation, let's say purple dye wants to reproduce. Purple dye can only contribute purple color to its offspring. It will prove that it was incorrect when the purple dye is going to reproduce. It will give, again, the two characteristics, the red and the blue color, will separate in the offsprings and these colors will be contributed by the purple dye, either red or blue, to the offsprings. So basically, it was not something, genetic information was not something that mixed in and was inseparable afterwards. So before we start talking about principles in more detail, let's clarify some of the definitions. A character is an observable feature. For example, color of a flower, the height of a plant, the shape of a seed, the color of the seed, we look at some of these characters. Trade is a particular form of character. For example, white flower, red flower, the flower color is, the flower color is a character and a specific type of character is a trait. So red flower is a trait, color of a flower is a character. Several characters are the ones which are transmitted or are inherited from one generation to the next generation. In the next module, we look at Mendel's experiments and how he came to these conclusions that genetic information, when the individual forms gametes, genetic information separates and is passed on to the gametes in separate packages or particles. We have to keep in mind that back then these experiments were done in mid-1800s to late-1800s. At that time, people did not have the concept of genes, mitosis, meiosis or the chromosomes. So it was a landmark achievement in science that these principles were established purely on mathematics by applying mathematical principles and statistical principles to this discipline.