The transitional phase between Palaeolithic and Neolithic age is known as Mesolithic age.

The Mesolithic age, also known as the Middle Stone Age, is the transitional phase between the Palaeolithic and Neolithic ages. It is characterized by significant changes in human society, including advancements in tool-making techniques, the development of agriculture, and the shift from a nomadic lifestyle to a more settled existence.

Key features of the Mesolithic age:
- Transition from hunter-gatherer to settled agriculture: During this period, humans began to domesticate plants and animals, leading to the development of agriculture. This shift from hunting and gathering to settled farming allowed for the establishment of permanent settlements and the development of a more complex social structure.

- Advancements in tool-making techniques: In the Mesolithic age, humans began to produce smaller and more refined tools, known as microliths. These tools were made by retouching small flakes of stone to create sharp edges, which were then attached to handles or shafts. Microliths were used for various purposes, including hunting, fishing, and crafting.

- Increased reliance on natural resources: As humans settled in one place and started practicing agriculture, they became more dependent on local natural resources. This led to an increased focus on the exploitation of local flora and fauna, as well as the development of specialized tools and techniques for resource extraction.

- Artistic expression and cultural development: The Mesolithic age saw the emergence of artistic expression through cave paintings, rock engravings, and figurines. These artistic creations provide insights into the social, religious, and cultural beliefs of the Mesolithic communities.

- Environmental changes: The Mesolithic age coincided with significant environmental changes, including the end of the last Ice Age. As the climate became warmer and more stable, new habitats and resources became available, allowing human populations to expand and adapt to different environments.

Conclusion:
The Mesolithic age marks a significant transitional phase in human history, bridging the gap between the Palaeolithic and Neolithic ages. It is characterized by advancements in tool-making techniques, the development of agriculture, and the shift towards settled communities. The Mesolithic age laid the foundation for the subsequent development of complex societies and the rise of civilization.