Delhi, officially known as the National Capital Territory (NCT) of Delhi, is a city and a union territory of India containing New Delhi, the capital of India. Situated in the northern part of the country, Delhi is bordered by the state of Haryana on three sides and by Uttar Pradesh to the east. It is a sprawling metropolis, which along with its neighboring satellite cities of Faridabad, Gurgaon, Noida, and Ghaziabad, forms the National Capital Region (NCR) of India. With a population of over 18 million residents as per the 2011 census, Delhi is the second most populous city after Mumbai in India and one of the fastest-growing urban areas in the world. The official language of Delhi is Hindi while English is also widely spoken and understood. Punjabi and Urdu are also commonly used, reflecting the city's diverse cultural fabric. The diverse ethnicity and religious backgrounds in the city have made it home to a broad range of cultures and traditions. Delhi's history is as old as the epic Mahabharata, where the city is described as Indraprastha, the home of the Pandavas. The city has been a witness to the rise and fall of many empires such as the Delhi Sultanate and the Mughal Empire. The remnants of this rich history are seen in the numerous monuments spread across the city, including the UNESCO World Heritage Sites of the Red Fort, Qutub Minar, and Humayun's Tomb. It also houses India’s largest and busiest airport, the Indira Gandhi International Airport. Geographically, Delhi is located on the banks of the Yamuna River and is characterized by its wide boulevards, green spaces, and a mixture of modern and colonial era architecture. The geography of Delhi includes the Yamuna flood plains, the Delhi ridge, and the Gangetic Plains. The climate is described as semi-arid with high variation between summer and winter temperatures and precipitation. Culturally, Delhi is known for its traditional festivals, art, crafts, music, dance, and cuisine which reflects a synthesis of various cultures. The city celebrates major Indian festivals such as Diwali, Holi, Eid, Christmas, and Guru Nanak Jayanti, a representation of its multi-ethnic society. Demographically, Delhi's population is a blend of people from various parts of India and the world. This mix of people has made Delhi a melting pot of diversity, enhancing the city's vibrant social tapestry and influencing its culture, language, and cuisine. Delhi is recognized for its street food, the heartiness of Mughalai cuisine, and for sweets like jalebi and kulfi. Furthermore, Delhi has a dynamic educational and political scene. It is headquarters to several central government bodies and is the epicenter of Indian politics. The city also boasts some of India's top educational institutions like the University of Delhi, Jawaharlal Nehru University, and IIT Delhi. Moreover, Delhi faces challenges such as air pollution, congestion, and socio-economic disparities. However, the city continues to expand with infrastructure developments and smart city initiatives. The Delhi Metro, a major urban mass-transit system, is an epitome of the city’s efforts to provide sustainable public transportation. With its vast history, a blend of cultures, and continuous growth, Delhi remains a city that represents the heart and soul of India.