What Is a QR Code? A Plain-English Guide
A QR code is a two-dimensional barcode that smartphones can scan and instantly open a URL, save a contact, connect to WiFi, and much more. You have probably scanned hundreds without thinking about what is happening. This guide explains QR codes from the ground up — what they are, how they encode data, and why they have become the go-to bridge between physical and digital.
Step-by-Step Guide
Understand the Structure
A QR code is a grid of black-and-white squares arranged on a light background. The three large squares in the corners are finder patterns — they tell the scanner which way up the code is. The rest of the modules encode your data.
Learn What Data QR Codes Can Store
QR codes can encode plain text, URLs, WiFi credentials, contact details (vCard), phone numbers, SMS messages, email addresses, and more. A standard QR code can hold up to 3,000 alphanumeric characters.
Understand Static vs Dynamic QR Codes
A static QR code permanently encodes data into the image — changing the content requires a new code. A dynamic QR code stores a short redirect URL instead; you can update the destination any time without reprinting. Dynamic codes also support scan tracking.
See How Scanning Works
When your phone camera points at a QR code, the camera app detects the finder patterns, decodes the binary data using Reed-Solomon error correction, then acts on the content type — opening a browser, dialling a number, etc.
Create Your First QR Code
Use the Keep Codes generator on this page. Choose a content type, enter your content, optionally customise the colors, and download as PNG or SVG. No sign-up needed and the code works forever.
Try It Now — Create Your QR Code
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Pro Tips
- QR stands for Quick Response — they were invented by Denso Wave in 1994 to track car parts.
- Modern smartphones read QR codes natively through the built-in camera app — no separate app needed.
- QR codes include error correction, meaning they still scan even if up to 30% of the image is obscured.
- Always test your QR code on at least two different phones before printing at scale.
- Dynamic QR codes are worth using for anything you might want to update — menus, event pages, promotions.
Frequently Asked Questions
Are QR codes free to use?+
Yes. Creating and scanning QR codes is free. Keep Codes generates unlimited QR codes at no cost. Dynamic QR codes with tracking analytics may require a paid plan on some platforms.
How long do QR codes last?+
A static QR code lasts forever as long as the image exists. A dynamic QR code lasts as long as the redirect service is active. With Keep Codes, your codes have no expiry date.
Can QR codes contain viruses?+
The code itself cannot contain a virus, but it can link to a malicious website. Only scan codes from sources you trust. Your phone browser's security features will warn you about known harmful sites.
What is the difference between a QR code and a barcode?+
A traditional barcode is one-dimensional and stores data in the width of vertical lines — typically just a number (up to 30 characters). A QR code is two-dimensional, stores thousands of characters, and can encode URLs, contact cards, and structured data.
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