In Hindu cosmology asserts that the current universe is one of many and that time extends into the endless future and the endless past in cosmic cycles. For example a cycle of 4 Yugas (great ages/eras, consisting of Krta, Treta, Dvapara, and Kali Yuga, lasting 1.728, 1.296, 0.864, 0.432 million years respectively) is called a Mahayuga (a cosmic era), and a cycle of 1000 Mahayugas form a Kalpa (8.64 billion years, in which the universe collapses into a bindu (a singularity) and starts again), and 72000 Kalpas form a Brahma cycle (a pan-dimensional cosmic cycle) which equates to 311.040 trillion years – in which not just the visible universe but all relative frames of reference – Space, Time, etc. dissolves and eventually after a equally long period of pralaya (a quiescent or unmanifest state) starts again. Mindboggling how Hindus thousands of years ago perceived the universe on such cosmic time scales that rivals today’s modern cosmology (while most of Western culture until the 20th century believed the Universe was created only in 4102 BC, under the heavy influence of Christian theology).
The Hindu calendar does not give that much importance to the year itself, as it does to the cyclicalness of life. Thus instead of having each year unique by naming it with a number, each of the Hindu years have a name, which repeat every 60 years (i.e. the cycle starts again every 60 years). The number 60 comes from the 60 year cycle of the nakshatras (constellations).
For instance, the Western calendar years of 2001, 2002, 2003, and 2004 are (in Tamil): விஷு, சித்திரபானு, சுபானு, and தாரண (vishu, chitrabAnu, subAnu, and tAraNa). The 60 year cycle starts with year பிரபவ (prabhava) and ends with year அக்ஷய (akshya). FYI, the current year, தாரண (thaarana), is the 18th in the cycle.
Note also, though the years are cyclical, the Hindu calendar does associate a cardinality to the year within a Yuga (i.e. at the end of the yuga the number is reset). The current Western calendar year of 2004 corresponds to the Hindu calendar 5106 (which is based on the start of the current yuga, the Kali Yuga – which corresponds to the Western calendar date of February 17, 3102 BCE; a Kali Yuga is about 432,000 years, so we still have a long way to go).
The Hindu new years day (as is with most indigenous new years day observances around the world) starts around mid-April (the most logical place to put start of the New Year, not in January as in the Christian calendar). The days of the week are also named after the Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn. Not so surprising, considering it is based on Hindu astrology (as is the origin of the Christian calendar days of week).
Note: the Tamil calendar differs from the calendar of other languages of India in that it is based on the sidereal year (the time taken by the sun to return to the same position in the zodiac), as opposed to the lunar year.