DOC files are word processing documents that contain formatted text, tables, charts, graphs, images, etc. Files in this format have '.doc' extension. It can be accessed using word processing software like Microsoft Office, OpenOffice, Apple Pages, etc. DOC is a popular format to create documents like resumes, letters, invitations and more.
PDF stands for Portable Document Format. The file extension of documents in this format is '.pdf'. PDF format is used to design documents that are consistent across platforms and devices. This format is used for documents such at brochures, resumes, flyers, and a lot more. PDF files can have multiple pages and can contain a lot of information.
XLS stands for Excel file format. The file extension of spreadsheets in this format is '.xls'. XLS is a proprietary spreadsheet file format developed by Microsoft and is used with Microsoft Excel. XLS files store data in tabular formats using rows and columns and are suited for multiple environments.