Every item is turned into a list of numbers that captures its meaning (an embedding; for text, MiniLM with 384 numbers), so similar items get similar numbers. The map is a UMAP layout of those numbers, fitted on your GPU: similar items sit together.
New items are placed beside their nearest neighbours as they arrive, and every so often the whole map is quietly re-laid out so it keeps fitting what has arrived (the project's names for these steps: Batched RevAdopt and NodeGardener).
Labels name a region by its most distinctive words; +N counts what arrived since Play. Click a label for the region, a dot for the item.