Diwali is a five day festival that honors the victory of good over evil and brightness over darkness. It celebrates Lord Ram and his wife Sita returning to their kingdom of Ayodhya, following Ram and monkey god Hanuman's defeat the demon King Ravana and rescue of Sita from his evil clutches. It's known as the "Festival of Lights" for all the fireworks, small clay lamps, and candles that are lit. The candlelight makes Diwali a very warm and atmospheric festival, and it's observed with much joy and happiness.

Holi

Holi is a two day festival that also celebrates the victory of good over evil, as well as the abundance of the spring harvest season. It's commonly referred to as the "Festival of Colors". People exuberantly throw colored powder and water all over each other, have parties, and dance under water sprinklers. Bhang (a paste made from cannabis plants) is also traditionally consumed during the celebrations. Holi is a very carefree festival that's great fun to participate in if you don’t mind getting wet and dirty.

Eid-al-Fitr (Ramadan)

One of the biggest religious festivals in India, Id and the month long fasting prior to that which is known as Ramzan is fervently celebrated by millions of Muslims all across the country. It is a great advantage to have Muslims friends around this time as you get to enjoy the Iftar Parties every evening during Ramzan and gorge upon some delicious sweet dishes on the day of Id. Cities such as Lucknow, Delhi and Hyderabad see joyous celebrations and fanfare during Id. The festival is also symbolic of the brotherhood and cultural uniqueness of India.

Raksha Bandhan

This is a festival that falls on the brightest night of Shravan month. Raksha Bandhan stirs up one of the deepest and noblest emotions - the abiding and chaste bond of love between the brother and the sister. On this day sisters tie a rakhi — which may be a colorful thread, a simple bracelet, or a decorative string — around the wrist of their brother(s). The word "raksha" signifies protection, and "bandhan" is an association signifying an enduring bond; and so, when a woman ties a rakhi around the wrist of her brother, she signifies her loving attachment to him. He, likewise, recognizes the special bond between them, and by extending his wrist forward, he in fact extends the hand of his protection over her.

Navaratri

This nine-day festival of the Hindus is celebrated in almost all parts of India in the month of Ashvina, and is marked by fasting and praying to different aspects of Devi. Literally 'nine nights', this nine-day period from the new moon day to the ninth day of Ashvina is considered the most auspicious time of the Hindu calendar. It is celebrated as Durga Puja in the state of West Bengal. Durga Puja is the most important and the most eagerly awaited festival of the state. It commemorates the victory of Durga over the demon Mahishasura. The nine different aspects of Devi are worshipped over the nine days.

Bibliography

http://traveltriangle.com/blog/famous-festivals-of-india/

http://goindia.about.com/od/festivalsevents/tp/Indiafestivals.htm