Exactly what is a natal or birth (genethliacal) horoscope? Dal Lee, in his Dictionary of Astrology, states: A horoscope is "a scope ['picture' or graphic representation] of the horo [hour], or view of the heavens [from an Earth perspective] at the hour of a person's [or anything's 'beginning'] birth: and when we say hour of birth we mean the exact minute." Therefore, the birth or natal horoscope depicts the positions of the heavenly bodies (Sun, Moon, planets) as viewed from the exact geographical location -- longitude and latitude (city, state, country) of the birth. Birth is generally considered (astrologically) to be the moment the newborn inhales oxygen for the first time -- adding (individually independent) air (the final element) to the already-existing essential elements -- fire (temperature), earth (physical presence), and water (liquids -- blood, other watery substances). And for other types of "births/beginnings," the moment an idea, question, or concept is first formed, fully conceptualized -- or "born."
Progressed Horoscope (or Horoscopes)
It has long been a tradition in Astrology, supported by centuries of use and validation, that a birth or natal horoscope should be moved forward (progressed) in such a manner that one day equals one year (the biblical year-day principle). For example, if the client is thirty year of age, a new chart is calculated based on the time/place of birth -- or the person's new longitide/latitude if significantly different -- for thirty days following the birth (called secondary progression) for a view of major influences in the individual's present life. And then by progressing (moving forward) the heavenly bodies for twelve months (or more) into the future, noting their aspects/changes as compared to the birth/natal horoscope, an insight into the coming year (trends/cycles) is revealed to the experienced astrologer. This information, combined with the transit chart, figures importantly in determining the client's "trends" or "update" to their natal/birth chart -- or the client's "forecast/roadmap" for the year ahead.
Transits Horoscope (or Horoscopes)
The transits horoscope shows the actual (present/future) planetary activity including aspects, shifts to other houses/signs and other considerations as they relate to a particular natal chart for the upcoming twelve months. Transit aspects to both natal and progressed planets are taken into account as they serve to outline the client's update or trends cycles. All heavenly bodies can be used but because of the overwhelming number of "routine" aspects formed by the Moon, Sun, and the inner planets -- Venus, Mercury, Mars, many astrologers concern themselves mainly with the activity of the outer planets -- Jupiter, Saturn, Uranus, Neptune and Pluto. Both the progressed horoscope and the transits horoscope -- as they relate to the client's unique natal chart -- form the basis for a meaningful trends overview for a future time period -- typically twelve months. To prepare a longer cycle reading period normally is not done because there is no way of knowing for certain how the client will actually respond to and work with the upcoming cycles, so an updated evaluation after a year is more likely to serve the client's best interests and needs by giving the astrologer a more current reference point from which to work.
Horoscopes are potentially possible for just about anything -- animal, vegetable, mineral, or act/action/activity -- for which a "birth" or intitial beginning time is known -- or to select a favorable time beforehand. For example, a horoscope can be prepared for a pet, the laying of a foundation for a house, a marriage -- after the fact. The problem, just as with natal/birth horoscopes, is ascertaining the accurate "birth" or starting time. A question (horary) horoscope can offer answers. For best times for starting a project, a when-to-act (electional) horoscope is called for. A compatibility (synastry) horoscope combines two natal charts into a third composite horoscope. The astrologer reading any non-human chart will need to know the nature of the item so the language and technique can be modified to more aptly apply to the subject of the horoscope under consideration, but the same general principles will apply no matter what the thing, subject or issue.