14. A method of associating advertisements to an input text comprising the steps of: a) (i) obtaining advertisement keyword meanings associated with said advertisements, each of the advertisement keyword meanings comprising a specific intended meaning of a word contained in the respective advertisement; (ii) indexing the advertisements according to the associated advertisement keyword meanings; (iii) storing said indexed advertisements in a database; and b) (i) obtaining a text in electronic form, said text comprising words used in a context; (ii) disambiguating said text to identify text keyword meanings of words contained in said text, each of said text keyword meanings comprising a specific deduced intended meaning of a respective word in the text, in view of the context of its usage therein; (iii) expanding at least one of the advertisement keyword meanings or the text keyword meanings, using their relevant semantic relations to other word meanings, to expand the list of advertisement keyword meanings or to expand the list of text keyword meanings (iv) searching said database of indexed advertisements to identify matches between the text keyword meanings and the advertisement keyword meanings; (v) extracting advertisements indexed to the advertisement keyword meanings matched to the text keyword meanings, said extracted advertisements comprising advertisements relevant to said text; and, (vi) providing results consisting of said relevant advertisements.
14. A method of associating advertisements to an input text comprising the steps of: a) (i) obtaining advertisement keyword meanings associated with said advertisements, each of the advertisement keyword meanings comprising a specific intended meaning of a word contained in the respective advertisement; (ii) indexing the advertisements according to the associated advertisement keyword meanings; (iii) storing said indexed advertisements in a database; and b) (i) obtaining a text in electronic form, said text comprising words used in a context; (ii) disambiguating said text to identify text keyword meanings of words contained in said text, each of said text keyword meanings comprising a specific deduced intended meaning of a respective word in the text, in view of the context of its usage therein; (iii) expanding at least one of the advertisement keyword meanings or the text keyword meanings, using their relevant semantic relations to other word meanings, to expand the list of advertisement keyword meanings or to expand the list of text keyword meanings (iv) searching said database of indexed advertisements to identify matches between the text keyword meanings and the advertisement keyword meanings; (v) extracting advertisements indexed to the advertisement keyword meanings matched to the text keyword meanings, said extracted advertisements comprising advertisements relevant to said text; and, (vi) providing results consisting of said relevant advertisements. 21. The method of claim 14 , wherein the step of disambiguating the text comprises using a knowledge base of explicit semantic relationships between word meanings.