New MPEP Released
The USPTO just announced a new version of the Manual of Patent Examining Procedure (MPEP). The last release was in 2020. The MPEP is binding on the more than 8,000 patent examiners at the USPTO so all US patent practitioners need to be familiar with it.
Many people use the basic HTML version of the MPEP (https://www.uspto.gov/web/offices/pac/mpep/index.html), which is what comes up in Google search results. Be careful – sometimes Google still surfaces results from non-current versions of the MPEP.
A former USPTO Examiner pointed me to the “Searchable MPEP” (https://mpep.uspto.gov/RDMS/MPEP/current), which I now use exclusively. It has a nice table of contents sidebar with collapsible hierarchies and, even better, has a decent search function at the top.