Documents are an essential component of clinical research. Essential documents are those that, individually and collectively, allow for a review of the trial's conduct and the quality of the data provided. All trials should have a written document describing the purpose of the trial, the criteria for inclusion and exclusion of participants, the methods used to generate the random allocation, the details of any restrictions placed on the conduct of the trial by the sponsor, any changes to the protocol made during the course of the trial, and the analysis plans for the results. The essential documents are as follows: trial registration document (also called a study plan), informed consent form, complete list of excluded and withdrawn subjects, all adverse events reports, and all source documents/data sets used in analyses. These documents serve three main purposes: they provide evidence of the ethical conduct of the trial; they help readers understand what was done and why; and they protect the rights of trial participants by documenting any changes to the trial or refusal to participate. Additionally, these documents alert others to problems with the validity of the findings from a trial, allowing researchers to take action if necessary. When planning a trial, it is important to consider how you will ensure its integrity and avoid bias.