Each column is one Semitic letter. Each row is one hand that wrote it. The rows are not a sequence but a family: the stemma down the left margin shows which script learned from which.

• Phoenician forks. One line stays at home and becomes palaeo-Hebrew, which the Samaritan community still writes. The other becomes Imperial Aramaic, the paperwork of the Persian empire, and nearly everything else descends from that.
• Hover any form for its name in that tradition, its codepoint, and what changed.
• Twenty-two letters, one order. Arabic later reordered its alphabet by shape, but the old sequence survives in the abjad numbering, which is why the columns still line up.
• Proto-Sinaitic is not in Unicode. That row is schematic line art after the Serabit el-Khadim and Wadi el-Hol inscriptions; every other cell is a real codepoint in a real typeface.
• Arabic and Syriac join their letters. The shapes here are isolated citation forms; in running text they fuse with their neighbours.

Datings are conventional approximations. The Nabataean row shows base forms only: the script also encodes a separate final form for most letters, which is where the joined Arabic hand comes from.

Elsewhere: The Same Idea · The Missing N · Flat-Foot · Polite Company · Signs for Sounds · The Second Alphabet · Brahmi's Daughters · The Same Word · Heartwood · Every Language Family