A document is any file that holds information you can read and edit
A document is a computer file that contains text, images, or both — something you open, read, and often change. The most common documents are letters, forms, reports, and spreadsheets. When you open a document on your computer or phone, you see the content displayed on screen, and you can usually type, delete, or rearrange what's inside.
Documents are different from other files because they're designed to hold information in a way humans can understand and work with. A photo file shows you a picture. A document file shows you words, numbers, or a mix of both that you can edit. The file type — the letters after the dot in the filename — tells your computer which program should open it.
You create documents every time you write an email, fill out a form online, or type notes in a program like Microsoft Word or Google Docs. You receive documents when someone sends you a contract to sign, a receipt, or instructions. Documents are the most common type of file most people work with on a daily basis.
Key Takeaways
- A document is a file containing text, numbers, or images that you can open, read, and usually edit on your computer or phone.
- Common document types include Word files (.docx), PDFs (.pdf), spreadsheets (.xlsx), and text files (.txt).
- The file extension — the letters after the dot in the filename — tells your computer which program to use to open the document.
- Documents are stored on your computer, phone, or in cloud storage like Google Drive or OneDrive, and you can share them with other people.
Common document file types and what they do
Different document types are built for different purposes. A Word document (.docx) is used for letters, essays, and reports where you want to format text with bold, italics, different fonts, and images. A PDF (.pdf) is a locked format that looks the same on any computer — it's used for contracts, receipts, and official forms because the layout won't change when someone else opens it.
A spreadsheet (.xlsx or .xls) organizes information into rows and columns, like a table. You use spreadsheets to track budgets, lists, or any data where you need to do math or sort information. A text file (.txt) contains only plain words with no formatting — no bold, no colors, no special fonts. Text files are simple and open in any program, but they're rarely used for formal documents.
Google Docs, Google Sheets, and Microsoft 365 create documents in their own formats, but you can download them as Word files or PDFs to share with people who don't use those programs. Most of the time, you don't need to think about file types — your computer opens the right program automatically when you double-click a document.
Where documents live and how to find them
Documents are stored in folders on your computer, just like papers in a filing cabinet. On Windows, you'll usually find them in "Documents" or "Downloads." On a Mac, they're in "Documents" or wherever you saved them. You can also store documents in cloud storage — services like Google Drive, OneDrive, or Dropbox that keep your files on the internet so you can access them from any device.
When you download a document from an email or website, it usually goes to your Downloads folder. You can move it to a different folder to keep it organized. If you can't find a document, use your computer's search function: press Ctrl+F on Windows or Command+F on a Mac, type the filename or a word from inside the document, and your computer will search for it.
Cloud storage has an advantage: if your computer breaks, your documents are still safe online. Many people now save documents to Google Drive or OneDrive instead of keeping them only on their computer. You can also share cloud documents with other people by sending them a link, and multiple people can work on the same document at the same time.
How to open a document
To open a document, find it in your file explorer or on your desktop and double-click it. Your computer will automatically open the correct program — Word for .docx files, Adobe Reader for PDFs, Excel for spreadsheets. If nothing happens when you double-click, the program that opens that file type might not be installed on your computer.
If you get an error message saying the program isn't found, you have two options. First, try right-clicking the document, selecting "Open with," and choosing a different program from the list. Second, download the program that matches the file type — Microsoft Word for .docx files, or free alternatives like LibreOffice or Google Docs. Many documents can open in multiple programs, so you have choices.
On phones and tablets, documents work the same way. Tap the file and the correct app opens automatically. If you don't have the app, your phone will suggest downloading it from the App Store or Google Play. Most phones come with a basic document viewer built in, so you can usually open any document even if you don't have the full editing program.
The difference between viewing and editing a document
When you view a document, you can read it but not change it. When you edit a document, you can add text, delete words, change formatting, or move things around. Some documents are locked so you can only view them — this protects the original from accidental changes. PDFs are often view-only, though some programs let you edit them.
If you open a document and can't type or make changes, it might be in view-only mode. Look for a button that says "Edit" or "Enable Editing" near the top of the window. Click it to switch to editing mode. Some documents are intentionally locked by the person who created them — they might require a password to edit, or they might be permanently read-only to protect important information.
When you edit a document, you should save your changes so they're not lost. Press Ctrl+S on Windows or Command+S on a Mac to save. If you're working in cloud storage like Google Docs, changes save automatically as you type. If you want to keep the original and make changes to a copy, use "Save As" to create a new file with a different name.
Sharing and sending documents to other people
You can share a document by sending it as an email attachment, uploading it to cloud storage and sharing a link, or giving someone access to edit it directly. To send a document by email, open your email program, click "Attach" or the paperclip icon, and select the document from your computer. The recipient will receive it as a file they can download and open.
Cloud storage is often easier for sharing. Upload your document to Google Drive, OneDrive, or Dropbox, right-click it, select "Share," and enter the email address of the person you want to share it with. You can choose whether they can only view the document or also edit it. They'll receive a link and can open the document in their browser without downloading anything.
When you share a document, think about what you're sharing. If it contains personal information like a Social Security number or bank account, use a secure method and only share with people you trust. Avoid posting documents with sensitive information on public websites or social media. If you accidentally share something private, most cloud storage services let you revoke access by changing the sharing settings.
Common problems when working with documents
The most common problem is opening a document and seeing strange characters or formatting that looks broken. This usually happens when you open a document in the wrong program — for example, opening a Word file in Notepad shows garbled text. The fix is simple: right-click the document, select "Open with," and choose the correct program.
Another frequent issue is a document that won't open at all. This can mean the file is corrupted, the program isn't installed, or the file type isn't recognized. Try downloading the correct program for that file type. If the document came from the internet, try downloading it again — sometimes downloads get interrupted and the file becomes damaged.
If you're working on a document and your computer crashes, you might lose unsaved changes. Most programs like Word and Google Docs have a recovery feature that saves your work automatically. When you reopen the program, look for a notification about recovered documents. To prevent this problem, save your work frequently by pressing Ctrl+S or Command+S every few minutes.
Frequently Asked Questions
What's the difference between a document and a file?
A file is any item stored on your computer — photos, videos, programs, and documents are all files. A document is a specific type of file that contains text or information you can read and usually edit. All documents are files, but not all files are documents.
Can I open a document on my phone?
Yes. Download the app that matches the document type — Microsoft Word for .docx files, Google Docs for Google documents, or Adobe Reader for PDFs. Open the app, find your document, and tap it to open. Many phones have built-in document viewers that work for common file types.
What happens if I don't save a document?
If you close a document without saving, any changes you made will be lost and the document will stay in its original state. Most programs warn you before closing and ask if you want to save. Cloud-based programs like Google Docs save automatically, so you don't have to remember.
Can two people edit the same document at the same time?
Yes, if the document is stored in cloud storage like Google Drive or OneDrive. Both people can open the document and edit it simultaneously — you'll see each other's changes appear in real time. This doesn't work with documents stored only on a computer; only one person can edit at a time.
Is a PDF a document?
Yes, a PDF is a type of document. It's a file format designed to look the same on any computer or device. PDFs are often used for official documents, forms, and contracts because the layout won't change when someone else opens it, unlike Word documents which might look different depending on the fonts installed.