What is creative brief in advertising?

Creative brief is a common document prepared to communicate and brief about a project among creative team, client servicing, accounts and clients. Generally, a creative brief is prepared by Account Manager and is then circulated among interested departments involved into the creative process of an advertisement.  It starts with the project title where overall objective of an ad campaign is introduced. After that an overview to entire project is gauged with reference to the background and necessity for the project.  In overview, project information, goals and measurable objectives are mentioned and provided through information.   
The next important step to creative brief is means to carry out message and the processes involved in developing an ad. These means normally are consisted of copy, design, printed materials and mailing.   After that come the mention of target audiences, who are the most important and the ultimate receiver of an advertising message. Here nature, behavior and response of target audience to an ad are assessed. Tone and image of the ad is next important point of concern in a creative brief.  Funny and casual, or formal, tone and imagery with specific visual goals are mentioned in Tone and image section of a creative brief.  And finally budget and schedule are discussed in the final without which a project cannot reach to its conclusion.