Just like the Rashis, the Nakshatras also break up the zodiac into equally spaced segments.

There are 27 Nakshatras, each taking up 13'20". The Nakshatras are also called lunar mansions, as the Nakshatra position of the Moon is an important use of Nakshatras. Each Nakshatra has a symbol, various attributes, and a planetary ruler. 

In order to clarify the use of Nakshatras, we will first explain the major differences between the use of Rashis and Nakshtras. Rashis are used to break up the chart into houses, as one Rashi corresponds to one house (the topic of the following lesson).

Nakshatras do not correspond to any house, or to anything comparable. The attributes of the Rashis are highly symmetric, with the order of male-female, and movable-fixed-dual repeating in a consistent pattern. The attributes of the Nakshatras are not like that at all, and their significance is not easily derived from a mathematical pattern as in the case of the Rashis. 

Rashis are fully responsible for the dignity of the Graha, such as being in exaltation, in Moolatrikona etc. Nakshatras play no role at all in determining the dignity or any other attribute of the Grahas. 

Rashis are used in the birth chart as well as in the divisional charts (vargas). Nakshatras are generally only used in the birth chart, and not in the divisional charts. 

Rashis are used in many of the strength calculations that constitute ShadBala, but Nakshatras are not used at all. 

The astronomically corresponding factor to a Rashi is the Solar month, whereas the Nakshatra is closest to the lunar day. (It takes one month for the Sun to pass through one sign, and it takes one day for the Moon to pass through one Nakshatra.) 

Signs aspect each other. Nakshatras do not have aspects. Nakshatras play a major role in the timing of the chart, and their order acts like a clock, activating the effects of the Grahas in the chart in a very particular order. The Rashis also have a similar relationship to the Grahas, but much less emphasized/used. 

In general, one can say that the Rashis divide the zodiac to reveal more visible, objective aspects of the chart, and create a division of houses that represent the major areas of life where the Grahas act in. Nakshatras divide the zodiac to reveal a more subjective cycle that is particularly relevant to understand our awareness and perception. 

The qualities of the Nakshatras are mostly derived from the symbols and mythological associations indicated in the Vedas. The accuracy and validity of these derived qualities can only be verified by the practicing astrologer