10. The method of claim 8 , wherein generating the first, second or third search expression further comprises filtering terms according to at least criteria based on term frequency within the first content item, the constituent of the second content item, or the collection of content items, or according to criteria based on term frequency within the first, second or third other content items.
8. The method of claim 6 , wherein the user also uses a collection of content items, and the method further comprises: receiving, by the search expression generator, the collection of content items, wherein the collection of content items comprises one or more web pages, posts to one or more social networking sites, posts to one or more blogs, posts to one or more online bulletin boards, documents, electronic messages, product descriptions, entertainment descriptions, advertisements, with each content item of the collection of content items having text divisible into a plurality of subtexts; and generating a third search expression, by the search expression generator, based on the collection of content items, to search second other collections of content items, through execution of the third search expression, wherein the third search expression includes a hierarchy of a plurality of nested juxtaposition sub-expressions corresponding with nesting of subtexts within content items of the collection of content items; wherein the third search expression is to be applied by the search engine operated on the same or a different computer system, to the second other collections of content items to generate a third search result.