Tools articles (page 5)
160 guides in this category.
Code 128 and Code 39: The Barcodes Behind Labels and Warehouses
Beyond product barcodes, many labels use Code 128 or Code 39. Learn what they encode and where you will meet them.
Read article →Data Matrix, PDF417 and Aztec: The Other 2D Codes
QR is the best-known square code, but others exist. A guide to Data Matrix, PDF417 and Aztec and where each appears.
Read article →How EAN-13 and UPC-A Product Barcodes Are Structured
What the digits under a product barcode mean: country or prefix, maker, product and the final check digit.
Read article →ISBN Barcodes on Books: What the Numbers Tell You
How the ISBN identifies a book edition, why it starts with 978 or 979, and how the barcode on the back cover relates to it.
Read article →School Admission Age Cutoffs: How They Work and How to Check Yours
Why school entry depends on age on a fixed date, how cutoff dates differ between systems, and how to check a child's eligibility precisely.
Read article →Age Limits in Competitive and Government Exams Explained
How minimum and maximum age rules, cutoff dates and relaxations work for entrance and recruitment exams, and how to verify your eligibility.
Read article →Calculate Age From a Date of Birth: A Step-by-Step Walkthrough
A worked example of turning a date of birth into an exact age, with the borrowing rules that make month and day counts come out right.
Read article →Calculating Your Age on a Past or Future Date
How to find your age on any date — for applications, planning or curiosity — and what changes when the 'as of' date isn't today.
Read article →How Many Days Until My Birthday? Counting Down the Right Way
How to work out the days remaining until your next birthday, including the leap-year and end-of-year cases that catch people out.
Read article →How Your Eyes Adjust to the Dark, and Why It Takes Time
The science of dark adaptation, why a bright torch can undo it, and how to protect your night vision.
Read article →LED Versus Incandescent: Why Modern Flashlights Use LEDs
How LED and old-style bulb torches differ in efficiency, durability and battery life, and why LEDs took over.
Read article →Warm Light Versus Cool Light: What Colour Temperature Means
What the Kelvin numbers on light bulbs mean, how warm and cool light affect mood and visibility, and which suits which task.
Read article →What Is a Lumen? Understanding How Bright a Light Really Is
A plain-English guide to lumens, lux and beam distance, and what they mean when you compare a phone flashlight with a dedicated torch.
Read article →Why Your Phone Gets Warm When the Flashlight Is On
What causes heat near the phone's flash, when it's normal, and simple ways to keep your phone cool and safe.
Read article →Aspect Ratio Explained: Why Photos Get Squashed or Cropped
What aspect ratio means, the common ratios (1:1, 4:3, 16:9), and how to resize without stretching your photo.
Read article →Hitting a Target File Size: How to Get a Photo Under 100 KB or 200 KB
Practical steps for meeting a strict file-size limit on online forms, using a mix of resizing, cropping and quality settings.
Read article →Lossy and Lossless Compression: What You Lose and What You Keep
The difference between lossy and lossless image compression, when each makes sense and how to avoid quality loss over repeated saves.
Read article →Passport and ID-Style Photos: A Digital Size and Quality Checklist
What to check when preparing a photo for a passport, visa, exam or job portal, from framing and lighting to dimensions and file size.
Read article →Pixels, Resolution and PPI Explained Without the Jargon
What pixels, resolution and PPI actually mean, why they matter when you resize a photo and how to think about them in everyday terms.
Read article →Error Correction in QR Codes: Why Damaged Codes Still Scan
QR codes carry built-in redundancy. See the four error-correction levels and what they mean for scratches, smudges and folds.
Read article →How a QR Code Is Built: Finder Patterns and Modules
A look inside a QR code: the three corner squares, the timing lines, the data modules and why a phone can read it from any angle.
Read article →QR Code Versions 1 to 40 and How Much They Hold
QR codes come in 40 sizes called versions. Learn how size relates to capacity and why shorter content makes an easier code to scan.
Read article →The First Barcode Scan: Wrigley's Gum in 1974
The story of the first product barcode scanned at a supermarket checkout, and how the idea took years to catch on.
Read article →The History of the QR Code: From Car Parts to Your Phone
How a Japanese engineer created the QR code in 1994 to track car parts, and how it became a worldwide tool.
Read article →