Scholarship is a conversation. When you cite, you are referring to another's work and giving them proper credit. You are giving your readers the opportunity to delve deeper into the topic by providing your references. You are also showing that you are building on scientific research from the past and how your ideas fit into the future!

Reference management software is designed to help you keep your references organized.   Some, like EndNote Desktop and Zotero, let you attach PDFs to a reference and annotate that PDF or keep notes about it.  You can also pull references from the software into word or a BibTeX file as needed.   Find a list of some software options below.  It is usually easy to move from one program to another if you decide what you're using doesn't have the features you need.