Web pages may be rendered from a main page data element and a plurality of embedded data elements, which are separately fetched by a browser. Herein is provided a web decoder which includes a learning engine adapted to receive human indications of data elements which are unimportant and accordingly to adjust the web decoder's procedures for determining which data elements are displayed to the user. The learning engine may receive human indications of important data elements and uses both types of indications in its further determinations. Optionally, rule generalizations are performed in a manner which searches for parameters which differentiate between important and unimportant data elements. The rule generalizations optionally concentrate on groups of data elements having at least a predetermined number of parameters having the same values for both important and unimportant data elements, reducing the chances that a generalization rule will find important data elements as unimportant.