A horoscope is the picture of the planets their position and aspects between them at a very moment of a birth. It could be a birth chart of a person or a birth chart of a question (Horary Astrology). If we wish to cast a birth chart we need the birth data: The date, time and the place of birth. 

The stars positions are not permanent. They keep moving around the zodiac. If we wish to cast a daily horoscope we need to have the data of the position of the stars for that day and the aspects between them.

A horoscope is subdivided in the 12 signs of the zodiac with 30 degrees each. There are 11 planets and 12, zodiac signs and 12 houses. The aspects between the planets are the degrees of separation between them.

There are several methods to predict the future. the position of the respective planet in a sign and in a house and its aspects to the cusps of the houses and the other planets determine what kind of life will the person have; however, In order to cast a horoscope for the future we need to consider the motions of the planets and aspects forming with significant position in the natal horoscope (the birth chart) . These motions are called transits.

We distinguish individual horoscopes and general horoscope. In a general horoscope we consider only  the planets position and the aspects between them  on the specific day/week/month.

Obviously a general horoscope cannot give an  accurate forecast  as much as an individual chart.