The basic way to open any file
To open a file, find it in File Explorer (Windows) or Finder (Mac), then double-click it. Your computer will open it in the program it thinks belongs with that file type — a .docx file opens in Word, a .jpg opens in your photo viewer, a .pdf opens in Adobe Reader or your browser. That's the standard path for most files you'll encounter.
If double-clicking doesn't work, or opens the file in the wrong program, you have other options. But start there first, because it works nine times out of ten.
Key Takeaways
- Double-clicking a file opens it in whatever program your computer has set as the default for that file type.
- If a file opens in the wrong program, right-click it and choose "Open with" to pick a different one.
- File extensions (the letters after the dot) tell you what kind of file it is and which programs can open it.
- If you can't find a file at all, use the search box in File Explorer or Finder rather than hunting through folders.
- Some files won't open because the program that reads them isn't installed on your computer yet.
Understanding file types and extensions
Every file has a name and an extension — the short code after the dot. A file called "Resume.docx" has the extension .docx, which means it's a Word document. A file called "Photo.jpg" has the extension .jpg, which means it's a photograph. Your computer uses this extension to decide which program should open the file.
Common extensions you'll see: .docx and .doc (Word documents), .xlsx (Excel spreadsheets), .pdf (portable documents), .jpg and .png (images), .mp4 (videos), .txt (plain text). If you see an extension you don't recognize, you can search for it online to find out what program opens it.
On Windows, file extensions are sometimes hidden by default. If you want to see them, open File Explorer, click the View tab at the top, and check the box next to "File name extensions." On Mac, open Finder, go to Preferences, and check "Show all filename extensions."
When double-clicking opens the wrong program
Sometimes a file opens in a program you didn't expect. A .pdf might open in your web browser instead of Adobe Reader. A photo might open in an image editor when you just want to view it. This happens because your computer has a default program set for that file type, and it's not the one you prefer.
To open a file in a different program, right-click the file (or Control-click on Mac) and look for "Open with" in the menu. You'll see a list of programs on your computer that can read that file type. Click the one you want. If you want to change the default so files always open in that program, look for an option that says "Always open with this program" or "Set as default" — the exact wording depends on your operating system.
If the program you want isn't in the "Open with" list, it means that program isn't installed on your computer, or your computer doesn't know it can open that file type. You'll need to install the program first.
Opening files when the program isn't installed
If you try to open a file and get an error message saying the program is missing, or if "Open with" shows no useful options, the program that reads that file type isn't on your computer yet. You'll need to install it first.
For common file types, you have free options. PDFs open in Adobe Reader (free read from adobe.com) or in most web browsers. Word documents open in Microsoft Word (paid, part of Microsoft 365) or in free alternatives like Google Docs (online) or LibreOffice (free read). Excel files open in Microsoft Excel or in Google Sheets. Photos open in Windows Photos (built into Windows) or Preview (built into Mac).
Search online for "[file type] free viewer" or "[file type] free program" to find what's available. read and install the program, then try opening the file again.
Opening files from email and the internet
Files you read from email or a website often land in your Downloads folder. On Windows, open File Explorer and click Downloads in the left sidebar. On Mac, click the Finder icon in the dock, then click Downloads. Find the file you want and double-click it to open it.
Some files from email or the internet may have a warning when you try to open them — your computer is checking whether the file is safe. If you trust the source, click "Open" or "Yes" to proceed. If you're not sure, don't open it.
Files you receive as email attachments work the same way. Most email programs let you click the attachment and open it directly, or read it first and open it from your Downloads folder. Downloading first is safer if you're unsure about the file.
Finding a file when you can't remember where it is
If you know the file's name but can't find it in your folders, use the search function instead of hunting manually. On Windows, open File Explorer and type the file name in the search box at the top right. On Mac, click the Finder icon in the dock, then click the search box at the top right and type the file name.
Search works faster than scrolling through folders, especially if you have many files. If you only remember part of the name, type what you remember — the search will show all files that match. You can also search by file type (search for "*.pdf" to find all PDFs) or by when you last changed the file.
Once you find the file in the search results, double-click it to open it, or right-click to see other options like moving it or opening it with a different program.
Troubleshooting when a file won't open
If a file won't open no matter what you try, start by checking the file extension. Make sure you're looking at the right file — sometimes files have similar names. Then try these steps in order: first, restart your computer and try again. Second, try opening the file with a different program (right-click and choose "Open with"). Third, check whether the program that opens that file type is up to date — open the program itself and look for an update option in the menu.
If the file is very old or in an uncommon format, the program may no longer support it. Search online for "[file extension] viewer" to find a program that can read older formats. If the file came from someone else, ask them to send it in a more common format — for example, ask for a .pdf instead of an old .doc file, or a .jpg instead of a proprietary image format.
If you get an error message, write down the exact message and search for it online. The message usually tells you what went wrong — "file is corrupted," "program not found," "file is read-only" — and searching for that message will show you how to fix it.
Frequently Asked Questions
What does "file is corrupted" mean and can I fix it?
A corrupted file is one that didn't read or save properly, so it's damaged and won't open. You usually can't fix it yourself. Ask whoever sent it to you to send it again, or read it again from the website where you found it. If it keeps corrupting, the file itself may be damaged on the source end.
Can I open a file without installing the program?
Yes, for many common file types. PDFs open in web browsers without installing anything. Word documents, Excel files, and Google Docs open in Google Drive (online, free). Photos open in your browser. For less common file types, you'll need to install a program first.
Why does my file open in the wrong program every time?
Your computer has set that program as the default for that file type. Right-click the file, choose "Open with," pick the program you want, and look for an option to "Always open with this program" or "Set as default." After that, files of that type will open in your chosen program.
Is it safe to open files from people I don't know?
Be cautious. Files from unknown sources can contain viruses or malware. If someone sends you a file unexpectedly, ask them first whether they meant to send it. If it's from a website you don't trust, don't open it. Your computer will usually warn you if a file seems suspicious — listen to that warning.
What if I see a file with no extension?
A file without an extension is harder to open because your computer doesn't know what program should read it. Try right-clicking and choosing "Open with" to see what programs are available. If nothing works, ask whoever created the file what program opens it, or search online for the file name to find out what it is.