A W3C Recommendation is the final stage of a ratification process of the World Wide Web Consortium (W3C) working group concerning the standard. This designation signifies that a document has been subjected to a public and W3C-member organization's review. It aims to standardise the Web technology. It is the equivalent of a published standard in many other industries.
In accord with the W3C Process Document, a Recommendation progresses through several maturity levels.
At the working draft level, the standard is published for review by "the community". A WD document is the first form of a standard that is publicly available. Commentary by virtually anyone is accepted, though no promises are made with regard to action on any particular element of said commentary.
At this stage, the standard document may likely have significant differences from its final form. As such, any who implement WD standards should be ready to significantly modify their implementations as the standard matures.
A candidate recommendation is a version of the standard that is more firm than the WD. At this point, the group responsible for the standard is satisfied that the standard does what is needed of it. The purpose of the CR is to elicit aid from the development community as to how implementable the standard is.
The standard document may change further, but at this point, significant features are mostly locked. The design of those features can still change due to feedback from implementors.
A proposed recommendation is the version of the standard that has passed the prior two levels. The users of said standard have had their say, and the implementors of the standard have likewise had a chance at providing input. At this stage, the document has been submitted to the W3C Advisory Council for final approval.
While this step is important, it rarely causes any significant changes to a standard as it passes to the next phase.
This is the most mature stage of development. At this point, the standard has undergone extensive review and testing, under both theoretical and practical conditions. This standard is now endorsed by the W3C as a standard for wide deployment in its problem domain.
A Recommendation may be updated by separately-published Errata until enough substantial edits accumulate, at which time a new edition of the Recommendation may be produced (e.g., XML is now in its fifth edition). W3C also publishes various kinds of informative Notes which are not intended to be treated as standards.