It starts with a handful of letters rather than an alphabet. Most designers draw n, o, H and O first, because those four settle the proportions, the weight, the stress and the counters, and everything else is built from the decisions in them. The word many people test with is adhesion: it contains a round, a stem, an ascender, a descender, a diagonal and a join, which is most of the problems in one word.
Then the spacing, which is where the work actually is. Every glyph carries a left and right sidebearing, and the goal is that the white space between any two letters looks equal. Not measures equal, looks equal, which is a different and much harder thing because an o and an I leave completely different shapes of gap. Get this wrong and no amount of good drawing saves the face. Get it right and nobody will ever notice, which is the job.
Kerning comes after, and only for the pairs that spacing cannot fix: AV, To, Ta, ry, and a few hundred to a few thousand others depending on the script. A well-spaced font needs little kerning. A badly spaced one cannot be rescued by any amount of it, and a designer adding their ten thousandth kern pair is a designer who should have gone back three steps.
Hinting is the instructions that tell a screen what to do when a curve falls between two pixels. It mattered enormously at 96dpi and matters much less now, which is why modern faces can afford complications that a 2005 screen font could not.
Then it is exported: OTF or TTF for desktops, WOFF2 for the web, which is the same outlines compressed by roughly half. And increasingly it is a VARIABLE font: one file holding the extremes plus the instructions for everything in between, so weight, width and optical size become continuous axes rather than separate files. The weight slider above is one file, not seven.
What you buy at the end is a licence, not a font, and it is worth reading once. Desktop licences are usually per seat, web licences per monthly pageview, app licences per title, and almost all of them forbid you from handing the file to your printer or converting it yourself. The most common way a small company breaks a type licence is uploading the desktop file to its own website, which is both the easiest thing to do and the one thing every EULA explicitly prohibits.