Guides & Tutorials

Tip 20% in New York, nothing in Tokyo, and round up in Paris. Tipping customs differ wildly — here's what's actually expected around the world.

That 25 MB PDF won't attach to your email. Here's why PDFs balloon in size and how to shrink them without turning the text and images to mush.

You sent a photo from your iPhone and your friend on Windows can't open it. That's HEIC. Here's why Apple uses it and how to convert it to JPG.

BMI is a useful screening number — and a widely misunderstood one. Here's what the categories mean, where BMI falls short, and how to read yours sensibly.

Swapping an 'a' for an '@' doesn't make you safe. Here's what actually makes a password hard to crack in 2026 — and why length beats clever symbols.

How many days until the deadline? How long since that date? Counting by hand is deceptively tricky. Here's how date maths works — and the easy way.

JPG, PNG and WebP each win in different situations. Here is exactly when to reach for each one, with real trade-offs on quality, size and transparency.

Stop guessing. This decision framework tells you exactly which format to use for photos, graphics, transparency, animation and print.

You can usually cut an image's file size by 60–80% with no visible quality loss. Here are the techniques that actually work, in priority order.

Images influence rankings through page speed, Core Web Vitals and image search. Here is the complete, prioritised checklist to get them right.

The habits that keep a site fast as it grows: right-size, modern formats, responsive images, lazy loading and a workflow you can repeat every time.

Seven concrete techniques, from the obvious to the overlooked, to make any image file smaller — and when to use each.

AVIF produces the smallest high-quality images available today. Here is how it stacks up against WebP and JPG, and whether you should switch.

Animated GIFs can be 10× larger than the equivalent video. Here is why, and how MP4 and WebM fix it without changing the experience.

AI can remove an image background in seconds. Here is how it works, where it shines, where it struggles, and how to get clean results every time.

Ever exported an image that looked dull or wrong online? Colour profiles are usually why. Here is what they are and which one to use.

A watermark can protect your work or wreck your image. Here is how to add one that deters copying without distracting from the picture.

Aspect ratio decides how your image fits every screen and feed. Here are the ratios that matter and how to crop without distorting or cutting off the subject.

Every common image format, compared side by side: compression, transparency, animation and the one job each is best at.