Content analysis is the process of examining some form of communication materials. Content analysis is used for purposes of description and inference. It involves extracting implicit and/or explicit information from content through the process of coding and classification. The variance in procedures can leave a study susceptible to threats of validity and reliability; thus, it is important to establish the content, type of content, coding units, approach, and coding analysis prior to beginning the analysis. Content analyses are also classified by various approaches, which, similar to types of analysis, are dependent on the focus and goals of the research, as well as the process of recording data. Content analyses have also been used to explore the portrayal of crime within the media. Content analyses are an essential part of criminal justice and criminology research. The type and approach used are dependent upon the goals of the study and the content being analyzed.