The word 'horoscope' literally means 'marker of time', being a record of heavenly bodies at a particular point in time. Most often the point in time is the moment of a person's birth, which is why 'horoscope' is used interchangeably with 'birth chart'.
In modern times the word horoscope has come to be synonymous with short daily readings and predictions offered in newspapers, magazines and the web. Astrology purists often look down on such popular forms of astrology, claiming that genuine horoscope readings should be performed by professionals on an individual basis.
Professional astrologers vary in their exact methodology. For example, some include the place of birth as part of the horoscope while others ignore it. Some believe that astrology can predict the future, others believe it can only assist people to become better prepared for whatever the future holds. Some use astrology in conjunction with other mystical arts (psychic powers, occult, etc), while others believe astrology is a purely scientific endeavor.
Skeptics look down on all forms of horoscope, pointing out that it is fairly easy to study groups of people who share similar birth charts. No credible studies have shown that people with similar horoscopes share similar personality traits.