What a "bitmap" actually is — and what it isn't

One of the stranger, lovelier ideas to come out of Bitcoin recently is that its blocks are places. Not just batches of transactions — but a vast grid of numbered districts, one per block, that people can name and "own." Newcomers hear the word "bitmap" and understandably get confused, partly because it's now used for two related-but-different things. Let's untangle it, honestly.

Where "bitmap" started: on Bitcoin

The original idea — often called bitmap theory — emerged in 2023 as a metaprotocol built on Bitcoin Ordinals, the system that lets people inscribe data onto individual satoshis. The theory is simple and poetic: treat every Bitcoin block as a numbered district. Block 792,435 becomes the district "792435.bitmap." The transactions inside each block become "parcels." To claim a district, someone inscribes its number, in order, on Bitcoin itself. It became a big community experiment in "digital land," living entirely on the Bitcoin blockchain.

That's the original, and if that's specifically what you want, you'd go looking for an Ordinals bitmap, inscribed on Bitcoin.

The other one: Bitmap in a Canister (on the Internet Computer)

Separately, the DOM project built something inspired by that idea, called Bitmap in a Canister (BIC). It borrows the beautiful part — every block is a district — but it is built on the Internet Computer (ICP), not on Bitcoin. It's a one-million-district canvas that lives inside an ICP "canister" (a smart contract), which is what makes it cheap, fast, and fully on-chain to interact with.

This is where we want to be crystal clear, because it would be easy to blur:

Bitmap in a Canister is an homage to the Bitcoin bitmap idea — not a Bitcoin Ordinals inscription, and not affiliated with it.

When you "own a day" on the DOM project's bitmap.media, here's exactly what happens: you pick a date, it's mapped to that day's Bitcoin block height (a real, public number), and you claim the matching district on ICP. What you receive is an on-chain BIC district recorded on the Internet Computer — a keepsake tied to that block number. What you do not receive is an Ordinals bitmap on the Bitcoin blockchain. Two different chains, two different objects, one shared inspiration.

So which is "real"?

Both are real; they're just different things, and neither is a substitute for the other. The Bitcoin Ordinals bitmap is the original community artifact on Bitcoin. BIC is DOM's own on-chain interpretation on ICP, designed to make the "own a meaningful day" experience simple and permanent. Which one is "for you" depends entirely on what you actually want — and you should buy either one only once you're clear on which chain it lives on.

We wrote this piece precisely so nobody claims a day thinking they've bought something they haven't. Read the fine print, know your chain, and then — if the idea of holding a date you care about appeals — it's a genuinely charming thing.