Explanation:

It is a collection of techniques used to maintain or grow plant cells, tissues or organs under sterile conditions on a nutrient culture medium of known composition.
It is widely used to produce clones of a plant in a method known as micropropagation. Advantages over traditional methods of propagation:
The production of exact copies of plants that produce particularly good flowers, fruits, or have other desirable traits.
To quickly produce mature plants.
The production of multiples of plants in the absence of seeds or necessary pollinators to produce seeds. The regeneration of whole plants from plant cells that have been genetically modified.
The production of plants in sterile containers that allows them to be moved with greatly reduced chances of transmitting diseases, pests, and pathogens.
The production of plants from seeds that otherwise have very low chances of germinating and growing, i.e.: orchids and Nepenthes.

To clean particular plants of viral and other infections and to quickly multiply these plants as 'cleaned stock' for horticulture and agriculture.
Plant tissue culture relies on the fact that many plant cells have the ability to regenerate a whole plant (totipotency).