What it is
An executable file is a program you can run - double-click it and your operating system starts doing what the file tells it to do. Common examples: .exe and .msi on Windows, apps on macOS, and ELF binaries on Linux.
Why it matters
Executables can be useful apps or malware in disguise. That’s why many are digitally signed: the signature helps verify who made the file and that it hasn’t been tampered with.
Smart safety basics
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Check the source: download from official sites/stores only.
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Look for a valid signature: right-click → Properties → Digital Signatures (Windows).
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Scan before running: use reputable anti-malware; avoid running unexpected attachments.
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Show file extensions: don’t trust icons—
invoice.pdf.exeis not a PDF. -
Least privilege: don’t run as admin unless you must.