FITALY is a keyboard layout that places the most commonly-used letters closest to the centre, to minimize finger movement while entering a word. Designed by Jean Ichbiah (Patent), it is specifically optimized for stylus or touch-based input. The name, FITALY, is derived from the letters occupying the second row in the layout (like QWERTY comes from the 1st row of standard keyboards)
The aim of the design is to optimize text entry by organizing keys to minimize key-to-key finger movement, allowing faster input through one-finger entry (compared to 10 fingers required to type efficiently on QWERTY layout). As compared to the 3-row QWERTY keyboard, FITALY has 5 rows with atmost 6 letters in a row (as against 10 on QWERTY).
Keys are arranged based on individual frequencies of letters in the English language, and the probability of transitions. The ten letters at the very center (i,t,a,l,n,e,d,o,r,s) are used 73% of the times when typing in English and with c,h,u,m added to the list, the number goes up to 84%. Keys are never more than 2 blocks away (vertically, horizontally or diagonally) from the current position. You nearly always find the next likely letter on a key very close to the one you just tapped.
Almost all of the text from this post exists on Wikipedia; but that’s because I updated the Wiki page after my research. Nothing feels better than giving something back to the community 🙂
More on Letter Frequencies at: