23. The system of claim 22 wherein the text mapping information included in the verification record corresponding to the annotation includes text offsets and a hash mask associated with a portion of the webpage content to which the annotation corresponds, and the second operations further comprise comparing the text offsets and the hash mask, included in the text mapping information included in the verification record corresponding to the annotation, with text properties of a portion of webpage content of the received current instance of the webpage that corresponds to the text offsets included in the text mapping information; and if the comparison results in a mismatch, determining that the portion of the webpage content of the webpage corresponding to the text offsets included in the text mapping information has been modified by the third party since the annotation was created, and if the comparison results in a match, determining that the portion of the webpage content of the webpage corresponding to the text offsets included in the text mapping information has not been modified by the third party since the annotation was created.
22. The system of claim 21 wherein the received annotations collection comprises: one or more verification records corresponding to the one or more annotations included in the annotations collection, where a verification record from among the one or more verification records includes permissions to and text mapping information associated with an annotation from among the one or more annotations included in the annotations collection to which the verification record corresponds; and one or more supplementary records corresponding to the one or more annotations included in the annotations collection, where a supplementary record from among the one or more supplementary records includes notes and addresses of cross-referenced webpages associated with an annotation from among the one or more annotations included in the annotations collection to which the supplementary record corresponds.