Navratri, a Hindu festival celebrated with great enthusiasm across India and other parts of the world, holds significant religious and cultural importance. The word "Navratri" is derived from two Sanskrit words: "Nav" meaning nine, and "Ratri" meaning night. As the name suggests, Navratri spans nine nights and ten days.

During Navratri, devotees worship different forms of the goddess Durga, known as Navadurga. Each day is dedicated to a different manifestation of the goddess, and specific rituals and prayers are performed accordingly.

Navratri is also associated with fasting, where devotees abstain from certain foods or follow strict dietary restrictions as a form of purification and devotion. Additionally, Navratri is known for its colorful and lively celebrations, including Garba and Dandiya Raas dances, where people gather to dance, sing devotional songs, and rejoice in the festive spirit.

The festival culminates with the celebration of Vijayadashami or Dussehra, marking the victory of good over evil. In many parts of India, effigies of the demon king Ravana are burnt to symbolize the triumph of righteousness.

The nine forms of Durga worshipped during Navratri are:

1. Shailaputri: The daughter of the mountain (Shaila), she symbolizes the power of Brahma, Vishnu, and Shiva.
2. Brahmacharini: The goddess who performed severe penance (tapas) to attain Lord Shiva as her consort.
3. Chandraghanta: The goddess who symbolizes peace, serenity, and prosperity.
4. Kushmanda: The creator of the universe, she is believed to have created the universe with her divine smile.
5. Skandamata: The mother of Kartikeya (Skanda), she represents motherhood and fertility.
6. Katyayani: The daughter of sage Katyayana, she is a fierce form of Durga.
7. Kaalratri: The fierce form of Durga who destroys ignorance and removes darkness.
8. Mahagauri: The goddess who is worshipped for peace and prosperity.
9. Siddhidatri: The granter of Siddhis (divine powers), she is worshipped by yogis and seekers of spiritual knowledge.

Navratri occurs twice a year due to its association with the lunar calendar and the change of seasons.

1. Chaitra Navratri: This Navratri falls in the Hindu lunar month of Chaitra, usually corresponding to March or April in the Gregorian calendar. It marks the beginning of spring in the Northern Hemisphere. Chaitra Navratri culminates with Ram Navami, the birthday of Lord Rama, on the ninth day.
2. Sharad Navratri: This Navratri occurs in the Hindu lunar month of Ashwin, typically falling in September or October in the Gregorian calendar. It coincides with the onset of autumn in the Northern Hemisphere. The tenth day of Sharad Navratri is celebrated as Dussehra or Vijayadashami, symbolizing the victory of good over evil.

These two Navratris have different significance and rituals associated with them. While both celebrate the divine feminine energy and the victory of good over evil, they are observed during different seasons and have distinct cultural and regional variations in how they are celebrated.