LOG File

What is a LOG file?

A LOG file is a text file that records events from an app, website, server, or operating system. Logs help developers and support teams understand what happened, when it happened, and what may have caused an error.

Common uses

• Troubleshooting crashes and error messages
• Tracking system events and background services
• Auditing activity (logins, actions, requests)
• Debugging websites, APIs, and apps
• Monitoring performance over time

How to open a LOG file

• Windows: Notepad, Notepad++, VS Code
• macOS: TextEdit, Console app, VS Code
• Linux: less/cat in terminal, VS Code
• Tip: For huge logs, use a viewer that can handle large files

Common problems

• File is extremely large and slow to open
• Timestamps are in UTC or another timezone
• Mixed formats (JSON lines, plain text, stack traces)
• Sensitive data may appear (tokens, emails, IPs)
• Rotation/compression creates related files (.log.1, .gz)

History

Logs have been part of computing since early multi-user systems where tracking events was essential for reliability. Today, logs are everywhere—from websites and apps to devices and cloud services—because they’re one of the fastest ways to diagnose problems.