Glossary

Plain-English explanations of the terms our apps touch. Short answers up top, longer reads if you want them. Updated whenever something changes.

Aurora & Space Weather

What is the KP index?

A 0-9 scale that tells you how active the geomagnetic field is, and whether the aurora is reachable from your latitude tonight.

What is the aurora oval?

The ring around each magnetic pole where the northern (or southern) lights are most likely to be visible at any given moment.

macOS & Mac apps

What is the Mac Services menu?

A right-click menu that lets any app pass selected text or files into any other app, including small tools you install.

What is the Mac menu bar?

The strip at the top of your screen and the icons on its right side, which third-party apps can extend with their own controls.

Why does my Mac say I have "Other" storage?

Apple lumps anything it cannot classify into Other. It is almost never the system files you fear it is.

What is CPU load on a Mac?

A simple measure of how busy your processor is right now, expressed as a percentage from 0 to 100 per core.

Files, catalogs & hashing

What is a file catalog?

A saved, searchable record of every file in a folder or on a drive, so you can find things without opening the folder.

What is a directory listing?

The contents of a folder shown as a list. Every Finder window is one, and so is the output of the ls command.

What is file metadata?

The information about a file that is not its contents: dates, size, format, camera settings, and more.

What is EXIF data?

The metadata a camera writes into a photo, including date, camera model, exposure, and often GPS location.

What is a checksum?

A short string computed from a file. Same checksum means identical files, so it is used to verify and deduplicate.

What is an MD5 hash?

A fast 32-character fingerprint of a file. Great for spotting duplicates, but not safe for security.

What is SHA-256?

A secure 64-character fingerprint used to verify downloads and prove a file has not been tampered with.

What is a duplicate file?

A second copy of the same content. Exact copies and near copies are different problems with different fixes.

CSV vs Excel for file lists

CSV is plain and portable. Excel keeps formatting and thumbnails. Which to pick when you export a file list.

What is a manifest file?

A list that describes the contents of a package or delivery, often with checksums to confirm nothing is missing.

Photos & images

JPEG vs PNG for upscaling

When you should pick one over the other, and why the wrong choice can lose detail after upscaling.

HEIC vs JPEG on iPhone

Apple's default photo format is smaller and sharper, but it trips up plenty of older tools. Here is when each makes sense.

What is neural style transfer?

The AI technique behind apps that turn photos into cartoons, anime, or oil paintings.

What is an iPhone duplicate photo?

Exact copies, near-duplicates, and burst frames are three different things. iOS only catches one of them.

Networking

What is Wi-Fi channel overlap?

Why your neighbour's router can slow yours down, and how to pick a channel that does not collide.

2.4 GHz vs 5 GHz Wi-Fi

Range versus speed, in plain English, and when to force a device onto one or the other.

What is an SMB share?

The protocol your Synology, Mac, or Windows machine uses to share files over a local network.

Developer / text tools

Regex cheat sheet

The small set of patterns you actually need 90% of the time, with examples.

What is Base64 encoding?

A way to turn raw binary into safe ASCII text, used in everything from email attachments to JWTs.

What is a JWT token?

A short, signed string that a server hands a client to prove who they are without keeping a session on the backend.

What is a delimiter?

The character that separates one field from the next - a comma, tab, semicolon, or pipe - and why CSV and TSV files rely on it.

Wellness & body

What is box breathing?

A 4-4-4-4 breathing pattern used by Navy SEALs, surgeons, and stressed-out office workers alike.

What is 4-7-8 breathing?

A slower technique meant to help you fall asleep, popularized by Dr. Andrew Weil.

Earthquakes & monitoring

What is the Richter scale?

The original earthquake magnitude scale, what it actually measures, and why it has mostly been replaced.