What Is a QR Code and How Does It Work?

By November 14, 2026

A QR code is a square pattern of black and white modules that stores information such as a web address, a Wi-Fi login or a contact card. When you point a phone camera at it, the phone reads the pattern and shows you what it contains. The name stands for Quick Response, because the code was designed to be read fast.

Where QR codes came from

QR codes were created in 1994 by Denso Wave, a Japanese company, to track car parts in factories. Normal barcodes could only hold a short number, while the new square format could hold much more and could be read from any angle. The format was released for free use, which is a big reason it spread to menus, tickets, posters and payments.

What is inside the pattern

Every QR code has a few standard parts:

  • Three large squares in the corners. These tell the scanner where the code is and which way it is rotated.
  • Data modules, the small squares in the middle that store your text or link.
  • Error correction data, extra information that lets a damaged or partly covered code still be read.
  • A quiet zone, the empty margin around the code that helps the scanner separate it from the background.

How scanning works

The phone camera finds the three corner squares, straightens the image, reads each module as a 1 or a 0, fixes small errors using the correction data and turns the result back into text. Then the phone decides what to do with it. A link opens in the browser, a Wi-Fi code offers to join the network, and a contact code offers to save a new contact.

How much can a QR code hold?

A single code can hold thousands of characters, but the more data you add, the denser and harder to scan it becomes. For everyday use, keep the content short. A short web address makes a clean, easy-to-scan code.

Common uses

  • Restaurant menus and table cards
  • Business cards and flyers
  • Guest Wi-Fi access
  • Event invitations and tickets
  • Product manuals and packaging

Make your own

You can create a free QR code in a few seconds with the QRIQO QR code generator. Choose a type, enter your details and download it as PNG or SVG.

QR Code Guides

How to Use QR Codes on Business Cards and Flyers

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A QR code on printed material connects paper to your online world. But a code that is too small, badly placed or missing a reason to scan will be ignored. These tips help you get it right. Business cards Business cards have little space, so keep it simple: Use a vCard QR code to share your contact details, or a link to your website or portfolio. Print the code at least 2 cm (0.8 in) wide. Put it on the back so the front stays clean. Keep the content short. Less data means a simpler, easier code. Flyers and brochures On a flyer, make the code about 2.5 to 3 cm wide and place it where the eye naturally ends, often the bottom corner. Always add a short call to action such as "Scan to see the menu" or "Scan to book". Posters For posters, size depends on distance. A useful rule is to divide the scanning distance by 10. For a poster read from 1 meter away, the code should be about 10 cm wide. Give people a reason to scan People scan when they know what they...

QR Code Error Correction Explained: L, M, Q and H

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Have you noticed that QR codes with a logo in the middle still scan? That works because of error correction, a feature built into every QR code. It lets the scanner rebuild missing data. How error correction works QR codes use a method called Reed-Solomon error correction. When the code is made, extra data is added next to your information. If part of the code is dirty, scratched or covered, the scanner uses the extra data to recover what is missing. The four levels Low (L): can recover about 7% of the code. Medium (M): about 15%. A good everyday choice. Quartile (Q): about 25%. High (H): about 30%. Best when adding a logo or printing in rough conditions. The trade-off Higher correction means more extra data, so the code becomes denser with smaller modules. A dense code needs more print size and a better camera to scan. That is why you should not always pick High. Which level should you choose? Short link on clean paper or a screen: Medium. Printed on packaging or o...

Is a Wi-Fi QR Code Safe? What to Know Before You Share One

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Wi-Fi QR codes are convenient, but they also deserve a little thought. The code contains your network name and password, so anyone who can scan it can join your network. What the code actually contains A Wi-Fi QR code is simply text in a standard format that includes the network name, the security type and the password. There is no encryption inside the code. If someone photographs it, they have your password. Where it is fine to display one Inside your home, in a private spot In a guest room or a rental property for guests only Behind the counter or in a staff area, if you do not want public access Where to be careful Do not post a Wi-Fi code on social media or in a public window unless it is an open guest network meant for everyone. Photos of codes spread quickly. Use a guest network Most routers let you create a separate guest network. Put the QR code for the guest network on display and keep your main network password private. Guests then cannot reach your computers, pr...

QR Code Colors and Contrast: What Works and What Does Not

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A black and white QR code is reliable, but you can match your brand colors too. The key is contrast, the difference in brightness between the code and its background. Scanners read brightness, not color. The golden rule The code must be clearly darker than the background. Think about how the colors look in a black-and-white photo. If the code and background look almost the same gray, a scanner will struggle. Combinations that work well Black on white Dark blue on white (the QRIQO default) Dark green on a pale yellow or white background Deep purple on white Dark red or maroon on white Combinations to avoid Yellow, light orange or light gray on white Red on green or blue on red, which look different to the eye but similar in brightness Light code on a dark background, because some scanners cannot read inverted codes Gradients or photos behind the code Tips for branded codes Choose a dark version of your brand color for the code. Keep the background white or very ligh...