Consensus is the default mechanism by which decisions are made on Librarybase, either for the project as a whole or a particular aspect.
The notion behind consensus on Librarybase is that carrying out a process for measuring agreement, like a poll, is not necessary if a discussion yields no dissent. Either everyone is satisfied with the decision, or does not care strongly enough to register an opinion. If there is disagreement, it is worth evaluating the disagreeing points of view to see if an alternative could be synthesized that addresses the concerns. Building consensus this way is robust and ultimately leads to a better outcome.
Consensus is achieved by default when an edit is made to a page and it is not reverted or challenged in any way. Reverting an edit can indicate the absence of consensus. Back-and-forth revert wars are very strongly discouraged.
Sometimes, disagreement persists, and for one reason or another, it is desirable to bring in the broader community for consultation and to formally decide on a path forward. These kinds of situations warrant a formal comment and decision process that is accessible to users of all experience levels and has explicit approval criteria that were agreed upon in advance.
As Wikipedia defines it
"Consensus," as Wikipedia defines it for it purposes, may reflect consensus in a broad sense, but is arrived by more complicated means in practice. It involves a combination of super-majoritarian rule, weighing arguments on the merits as a judge would, and synthesizing a middle ground like an arbitrator or mediator would. An outcome reflects "consensus" when the number of people who would object is so few they have no choice but to acquiesce and move on. What constitutes a sufficient percentage will depend on the scenario. At the scale of Wikipedia, this basically works, and there are mechanisms to bring more people into the process as earlier steps fail.
If you are coming here from Wikipedia or Wikidata, that is probably the notion of consensus you are familiar with. It mostly applies to Librarybase as well, but where it falls apart is formal decision-making where informal processes break down. To the extent formal process is desirable, there is no uniform process that is agreed upon, and the ability to engage or participate in the process largely depends on your experience. This is not accessible to newcomers and is easy to manipulate. For Librarybase, a preferable alternative would be a formal comment request process when more informal processes break down.