The most well-known branch of astrology, natal astrology (or genethliacal astrology) seeks to understand an individual's life and future through an astrological chart cast for the moment of birth.
Natal astrology is the most popular or well-known branch of the art because most people are introduced to astrology through it as a concept. The grand majority of individuals will begin by exploring their own birth chart and then move on to the birth charts of others close to them. It is only after spending some time here that people discover the other branches.
It may seem strange to many that natal astrology is listed so far down the branches in the site directory, as if the other branches ought to come before it. This is a reflection of the organization of many classical texts where natal astrology is discussed far into the back. In Bonatti's 10 volume Book of Astronomy, nativities is book 9. William Lilly's three volume text Christian Astrology discusses nativities in book three after discussing the basics of astrology in book one and horary in book two.
The purpose of natal astrology is two-fold. Initially the astrologer seeks to investigate each area of life and distinguish the good or productive areas from the bad or unproductive places. This can be as easy as letting an individual know that their relationship with their father will be positive and he will leave them a good inheritance, but that their marriage life will be rocky at best. The second step is to predict when different areas will be active and what the results of that activity will be.
The second, predictive step of natal astrology is done through the utilization of time lord techniques. A time lord technique is any number of available techniques that identifies when certain planets or houses are activated or "turned on" for an individual. This typically marks important events happening in that area for that person with the type and quality of events being determined by placements in their natal chart.
There are a number of time lord techniques available. Hellenistic astrology seemed to favor Aphesis or Zodical Releasing, Annual Profections, and Ascensional Times. The medieval era emphasized concepts like the Revolution or Solar Return, Firdaria, and Directions. Transits have been used throughout the tradition, but they are always the last thing considered as transits to planets that are not activated by some other time lord technique were judged to be ineffective.
It is recommended that natal astrology comes later in a student's learning as it works with charts that can take decades to fully manifest themselves. While the initial delineation will feel familiar to students of horary and electional, the timing techniques that must logically follow will feel very foreign.