The document summarizes the key sectors of India's economy - primary, secondary, and tertiary - and how they have evolved over time. It notes that agriculture originally dominated the primary sector but as the economy developed, the secondary sector grew through industrialization and the tertiary sector expanded through the growth of services. While the tertiary and secondary sectors have increased in GDP contribution, agriculture still employs the majority of the workforce. The sectors are also interdependent, as the document demonstrates through the example of a cold drink's production relying on activities in all three sectors.