博士后，又称博士后研究员，指那些在取得博士学位之后在大学或科研机构中有限期地专门从事相关研究或深造的人。博士后工作的机构称为“博士后科研流动站”或“博士后科研工作站”。作为有期限的工作（研究）人员，在工作期满后，必须退出博士后站点。

一个博士后位置从本质上来说就是一个工作（研究）岗位，它通常为有限期的，从6个月到5年不等。博士后的资助形式常为工资或奖学金。设置一个博士后岗位或从事博士后研究的理由通常有：

A postdoctoral researcher is a person professionally conducting research after the completion of their doctoral studies (typically a PhD). The ultimate goal of a postdoctoral research position is to pursue additional research, training, or teaching in order to have better skills to pursue a career in academia, research, or any other fields. Postdocs often, but not always, have a temporary academic appointment, sometimes in preparation for an academic faculty position. They continue their studies and/or carry out research and further increase expertise in a specialist subject, including integrating a team and acquiring novel skills and research methods. Postdoctoral research is often considered essential while advancing the scholarly mission of the host institution; it is expected to produce relevant publications in peer-reviewed academic journals or conferences. In some countries, postdoctoral research may lead to further formal qualifications or certification, while in other countries it does not.