Nakshatra (Sanskrit: नक्षत्रम्, Nakṣatram) is the term for a lunar mansion in Hindu astrology and Buddhist astrology. A nakshatra is one of the 27 (sometimes 28) sectors along the ecliptic, with each sector named after a prominent star or asterism within or close to it. In Western astronomical terms, a nakshatra broadly corresponds to a constellation. Every nakshatra is further divided into four padas, literally meaning "steps".
According to the Vedas, the list of nakshatras begins with Krittika. It has been argued that this was because the Pleiades may have marked the start of the year when the Vedas were compiled, presumably at the vernal equinox. In more recent compilations, however, the list begins from the point on the ecliptic directly opposite the star Spica, known in Sanskrit as Chitrā. This starting point translates to Ashwinī, located in the modern constellation of Aries. Such compilations may therefore date from the centuries when the sun passed through Aries at the time of the vernal equinox, and this reckoning may have been called Meshādi, or the "start of Aries". The earliest astronomical text known to list the nakshatras is the Vedanga Jyotisha.
In classical Hindu scriptures, including the Mahabharata and the Harivamsa, the creation of the asterisms is attributed to Daksha. The Nakshatras are personified as the daughters of Daksha and as the wives of Chandra, the Moon god. According to the tradition, when Chandra neglected his other wives in favour of Rohini, his father-in-law cursed him with leprosy and decreed that the Moon would wax and wane each month. In an alternative tradition, the Nakshatras are described as the daughters of Kashyapa.
The nakshatra is one of the five elements of a Pañcāṅga, the traditional Hindu almanac. The other four elements are Tithi, Nityayoga, Karana and Vāra.
Adapted from the English Wikipedia article on English Wikipedia page for Nakshatra