Space the word.

Kerning is the space between two particular letters, adjusted so that a word reads as one even texture. Tracking, or letter-spacing, changes every gap in a line by the same amount. A type designer first gives each letter its own space on either side, then kerns the pairs that still look wrong, such as AV, To or LY.

In Space the word you do that work by eye: you place each letter yourself, then see the spacing the typeface’s designer gave it.

The two ends of each word stay fixed. Drag the letters and signs between them along the line, or pick one from the row of letters and nudge it with the − and + buttons or the arrow keys. When the word looks even, check it: your letters stay red, and black ones slide to where the typeface sets them, so you see every gap you missed.

A run is ten words over four levels, Notice, Tune, Balance and Punctuation: from a three-letter warm-up to words with dashes, commas and ampersands, set in DM Sans, Instrument Serif and DM Mono. The base set is the same for everyone. Play another set for ten new words, challenge a friend with a link to yours, or practise a single word or level.

Only the gap you leave counts. A letter scores 100 when it nearly overlaps its place in the typeface, and its points fall in a straight line to 0 at a gap plain to see. A word scores the mean of its movable letters, and the run the mean of its ten words, out of 100.

Where a letter started never counts, and neither does the clock. The allowance is widest on Notice and narrows up to Balance.

Letters are not boxes. Two straight stems, as in HI, face each other along their full height. A round letter beside a straight one, as in HO, meets the gap at one point and leaves white above and below it, so it has to sit closer. Diagonals, as in AV, leave open triangles and tuck into each other.

Set every gap to the same measured distance and the word looks patchy: dense where stems meet, loose around O, A and V. Good spacing evens out the area of white between letters, not the distance. That is optical spacing, and it is what your eye judges here.

• Look at the white between the letters, not at the letters.
• Squint or lean back. A blurred word shows the dark and pale patches a sharp one hides.
• Work inwards from the fixed ends, settling the pairs beside them first.
• In DM Mono every letter takes the same width, so their centres fall at nearly equal steps.
• Study each reveal. After a few words you start to see how a typeface spaces round, straight and diagonal letters.

Spacing is one of six skills in the balance test, a typography eye test in twelve rounds. The other five are overshoot, optical centre, detail, slant and weight.