Short answers, pulled from the story.
The word Hindu began to acquire religious connotations in the 14th century. Before this period, the term functioned solely as an ethno-geographical marker for people living beyond the river Indus. The poet Vidyapati used the phrase Hindu dharma in 1380 to contrast cultures, signaling the shift from a regional identity to a distinct religious one.
The British colonial legal system created a legal fiction that grouped Buddhists, Jains, and Sikhs under the umbrella of Hinduism. This administrative categorization persisted until the mid-20th century and effectively erased doctrinal differences between these distinct traditions. Colonial studies constructed the term to imply people who adhered to an ancient, default religious substratum.
The Hindu population has spread far beyond the Indian subcontinent with approximately 1.17 billion adherents worldwide. This group represents 14.9% of the global population, and projections suggest the number will grow to 1.4 billion by 2050. While 95% of Hindus reside in India, significant communities exist in Nepal, Bangladesh, Indonesia, and Pakistan.
The ideology of Hindutva was codified by Vinayak Damodar Savarkar while he was a political prisoner of the British colonial authorities. This movement emerged in the 1920s in Maharashtra as a direct reaction to the Islamic Khilafat Movement. The concept sought to reform Indian laws and define the nation in terms of Hindu values.
Hinduism lacks a single prophet, a central governing body, or a unified set of dogmas. The Supreme Court of India has described the Hindu religion broadly as a way of life that does not subscribe to any one philosophic concept. A Hindu may be polytheistic, monotheistic, pantheistic, or even an atheist and still be considered a Hindu.