PDF (Portable Document Format) is a file format that has captured all the elements of a printed document as an electronic image that you can view, navigate, print, or forward to someone else and preserves the original graphic appearance online. PDF was introduced to ease the sharing of documents between computers and across operating system platforms when you need to save files that cannot be modified but still need to be easily shared and printed. A full-text database is a compilation of documents or other information in the form of a database in which the complete text of each referenced document is available for online viewing, printing, or downloading. In addition to text documents, images are often included, such as graphs, maps, photos, and diagrams. A word document is a microsoft word document with content formatted in the internationally accepted research journal formats.