Reference management is when you use specific tools to help you organize the references you find during a literature review search.
Zotero--https://www.zotero.org/ Zotero is a free, open source reference management tool that helps you collect, organize, annotate, cite, and share research sources including .pdf's images and other files. It also generates references and bibliographies in various styles.
EndNote https://endnote.com/, is a reference management software application that allows you to store, organize and cite references, as well as create and format bibliographies. (You must buy EndNote)
RefWorks, https://refworks.proquest.com/ is a Web-based citation manager that allows you to create your own personal library of citations by importing references from databases and other online sources. RefWorks automatically formats your the in-text citations and references list for papers and manuscripts.