 Take a look at the organisms here. We have a tiger, we have some high viscous flowers, a mushroom and some monkeys. If we were to study these organisms, where would we start? Where would we even begin? These are quite different from each other, right? A monkey is quite different from a mushroom. Well, classification helps us do just this. Classification groups organisms based on any similarities or differences they have, which makes it easier to study those organisms. Taxonomy involves classifying organisms into different groups or categories. Taxonomy has been in practice for a long time. Greek philosopher Aristotle was one of the earliest people to categorize organisms that he could see around him into different categories. So he saw that organisms could be classified into two basic categories, plants and animals. Maybe he developed this because he saw that some organisms like plants, they couldn't move, they were stationary while animals could move and then plants didn't eat food while animals ate food. He further classified plants into medicinal and agriculture based on how they were used and into shrubs and trees based on how they grew and he also classified animals into whether they gave birth or laid eggs or had blood or didn't have blood. Carl Linnaeus was a biologist who brought in structure and organized the taxonomy. So taxonomy involves classifying organisms into different groups or categories and each of these category is called a taxon and the plural form is a taxa. Let's take a look at the different taxonomic categories. So taxonomic categories are not horizontal. It's not like this tax on A, tax on D, tax on C, etc. Instead there is a clear taxonomic hierarchy which means that there is rank. Organisms are classified into a least inclusive category which includes organisms that share the most number of common characters and then as we go on and on there comes a most inclusive category which means that these organisms here they share the least number of common characters. So what are these least and most inclusive categories? Well there are a lot of ranks in between this and this. Let's take a look at those individual ranks or taxon. First we have the species, the genus, then family, order, class, phylum for animals and division for plants and kingdom. Here species is the least inclusive category while kingdom is the most inclusive category. Organisms are classified into the same species if they share the maximum number of common characters and two organisms that are classified in the same kingdom share the least number of common characters. So let's take a deep look at the different taxon levels. We'll start with species. So any organism that you see is a species. For example a tiger is a species, a lion is a species and a leopard is a species. You can say that they are species also because you can clearly differentiate a tiger from a lion. You wouldn't see a lion and say hey that's a tiger. So these organisms are individual species. So if you take a look at the scientific name here that's given for tiger, lion and leopard you can say that it's something called pantera tigris, pantera leo and pantera pardus. So what does this pantera mean here? Well pantera signifies the next level or the next higher taxonomic rank of tiger which is the genus. So the fact that tiger, lion and leopard have the same name pantera as the genus indicates that they all belong to the same genus pantera. So a genus is a collection or a grouping of closely related species. If we take an example of plants, solanum is a common plant genus which includes species like potato and tomato. So next is family and a family is made up of closely related genera which is the plural form of genus. So let's continue with the example of pantera. So along with pantera there's another genus felis which are classified under the family felidae. So this genus felis includes common domestic cats. When we talk about the example of plants you have the genus capsicum which along with the genus solanum is classified under the family solanaceae. This is again a huge family. The next taxonomic rank is order which includes a collection of closely related families. So pantera and felis belong to the family felidae which along with the family canidae is classified in the order carnivora. Canadae includes all the dogs. So dogs and cats are classified under the same order carnivora. Here if you see that the common characters can be the fact that they're all carnivores. The family solanaceae is classified under the order solanales along with another family convovelceae. This family convovelceae includes species like sweet potato. After order comes class. So class includes all closely related orders. So when we continue with the example of carnivora, carnivora and the order primata and rodentia are all classified in the class mammalia which means that they're all mammals including humans. We belong to the order primata and rats and squirrels etc belong to the order rodentia. We talk about the example of plants. The order solanales is classified under the class polymonials. So the next taxonomic category is phylum for animals and division for plants. All closely related animal classes are classified into the same phylum. For example mammalia which includes all the mammals, avis which includes the birds and reptilia which includes all the reptiles. They're all classified under the phylum chordata. So that means that they're all chordate which means that they share characteristics of chordates such as having an autocord or a post anal tail. We talk about the example of plants. All the plants that were classified under the class polymonials are classified under the division magnonium phyta. The last and the final taxon of classification is kingdom and this is the highest degree of categorization. All animal phyla which is the plural form of phyla are classified in the kingdom animalia. Apart from chordata we have other phylums such as arthropoda which for example includes insects. All plant divisions are classified under the kingdom plantae. What can we learn from this? It means that an organism can be classified as an animal if it has similar characteristics like eating food and having the ability to move around etc and organisms can be said to be plants if they perform photosynthesis to produce their own food don't move around etc. Taxonomy is also used in the field of systematics. What systematics does is that it uses taxonomy to understand the evolutionary history of organisms and to understand the evolutionary relationship between organisms. But recently systematics has been developed into a field that includes not just understanding the evolutionary history of organisms but also in identifying, describing and classifying different organisms.