Cladistics is the classification of organisms based on evolutionary as well as genetic relationships. It is a method of classification that groups organisms based on shared ancestry. Cladistics uses a system of nested hierarchies to show the evolutionary relationships between different groups of organisms.

There are several key concepts that underpin cladistics:

- Clade: This is a group of organisms that share a common ancestor. A clade is defined by the presence of a set of shared characteristics, called synapomorphies. Any organism that has these characteristics belongs to the clade.
- Phylogeny: This is the evolutionary history of a group of organisms. It shows the relationships between different groups and the order in which they evolved.
- Homology: This is the similarity between two structures that is due to shared ancestry. For example, the wings of birds and bats are homologous structures because they both evolved from a common ancestor that had wings.
- Convergent evolution: This is the evolution of similar structures or characteristics in unrelated organisms. For example, the wings of birds and bats are an example of convergent evolution because they evolved independently in each group.

Cladistics is used to create a cladogram, which is a diagram that shows the evolutionary relationships between different groups of organisms. The more recently two groups shared a common ancestor, the more closely related they are on the cladogram.

Overall, cladistics is a powerful tool for understanding the evolutionary relationships between different groups of organisms. By grouping organisms based on shared ancestry, it allows scientists to make predictions about the characteristics of different groups, and to better understand the patterns of evolution that have shaped the diversity of life on Earth.

Cladistic is a method of classification in which plants or animal are placed into taxonomic groups according to the phylogenetic or evolutionary relationships.