Guides
Short, practical explainers backed by tools: read the guide, then apply it right away on the same page.
How to calculate percentages: formulas with worked examplesAlmost every percentage question is one of six patterns. Learn the formula for each, see a worked example, and avoid the traps that catch even finance teams.How to count the days between two datesCounting days sounds trivial until you hit leap years, 'inclusive' deadlines, weekends and bank holidays. Here's how to get it right every time.How prayer times are calculated, and why apps disagreeThe five daily prayer times follow the position of the sun. Astronomy gives exact answers, but organisations choose different angles and conventions, which is why two apps can differ by several minutes.BMI explained: how it's calculated and what it doesn't tell youBody Mass Index is a quick screening number based on height and weight. It's useful for populations, but for individuals it needs context such as waist size, age and muscle mass.Core Web Vitals explained: LCP, INP and CLSCore Web Vitals are Google's three metrics for real-world page experience: loading, responsiveness and visual stability. Here is what each means and how to fix it.Internet speed explained: what your speed test results meanA speed test gives you four numbers. Here's what each means, how much you actually need for streaming, gaming and video calls, and what to do when it's slower than you pay for.301 vs 302 redirects: which one should you use?Use a 301 (or 308) when a URL has moved for good and a 302 (or 307) when the move is temporary. The details below cover SEO, chains, loops and server configuration.How to speed up your website: what actually makes a differenceMost slow websites are slow for the same few reasons. Measure first, fix the biggest bottleneck, then repeat. Here is the order that pays off fastest.What is an SSL certificate, and how do you fix SSL errors?An SSL (really TLS) certificate lets browsers verify your site and encrypt the connection. Getting one is free; keeping it valid and configured correctly is where sites trip up.Is the website down for everyone or just me?Before you panic or call your host, spend two minutes working out where the problem is. The cause is usually DNS, an expired certificate, the server, or your own connection.Open Graph and Twitter cards: how to get perfect link previewsWhen someone shares your link, the preview card is built from a few meta tags. Set them once per page and your links stop showing the wrong image or a blank box.Robots.txt: syntax, examples and the mistakes to avoidRobots.txt tells crawlers which parts of your site not to crawl. A single wrong line can hide your whole site from Google, so it pays to understand the rules.Schema markup and JSON-LD: a practical guideStructured data describes your page in a format machines understand. Done right, it helps search engines interpret your content and can unlock rich results.How to write title tags and meta descriptions that get clickedYour title and description are your ad in the search results. A clear, specific snippet can lift clicks without changing your ranking at all.XML sitemaps: format, limits and how to fix common errorsA sitemap is a list of the URLs you want search engines to know about. It doesn't guarantee indexing, but a clean one helps crawlers find new and updated pages faster.DNS records explained: A, CNAME, MX, TXT and the restDNS is the internet's address book. Knowing the handful of record types that matter lets you move hosts, connect email and debug outages with confidence.SPF, DKIM and DMARC explained: why your emails go to spamMissing or broken authentication records are the most common reason business email ends up in the spam folder. Three DNS records fix most of it.Image optimisation for the web: formats, sizes and compressionImages are usually the heaviest part of a web page. Choosing the right format, size and loading strategy can cut page weight by more than half with no visible loss.How QR codes work: a practical guide for print and businessA QR code is a grid of black and white squares that a phone camera turns back into text or a link. A few technical choices decide whether it scans reliably.How to create a strong password you can actually live withLength beats complexity, uniqueness beats cleverness, and a password manager beats your memory. Here's what current guidance actually recommends.How loan interest works: repayments, APR and compound interestYour monthly repayment comes from one formula. Once you understand it, comparing loans, mortgages and savings offers becomes much easier.How to calculate VAT: adding and removing VAT with examplesAdding VAT is a multiplication; removing it is a division. Here are the formulas, examples for the UK and EU, current rates and the most common mistakes.