Naive rollups, also referred to as layer 2, is an upgrade to Azimuth implemented in 2021 that reduces Ethereum gas costs associated with Urbit ID transactions and friction associated with using cryptocurrency in general.
This system allows batches of Urbit ID transactions to be submitted together as a single transaction using an urbit node known as a "roller". The PKI state transitions resulting from these transactions are computed locally by your ship rather than by the Ethereum Virtual Machine.
Due to the dramatically reduced cost, Tlon offers their own roller that is free for ordinary public use. This enables new users to get started with a permanent Urbit ID without any prior knowledge of Ethereum, cryptocurrency, or blockchains.