Content filtering, ordering by relevance, and caching

A computer readable storage medium containing computer executable code for organizing a plurality of content items, said computer executable code comprising:

• (a) code for assigning to each content item a content item array, wherein each ordinal of said content item array indicates a characteristic of said content item;
• (b) code for applying a content filter to said plurality of content items, said content filter including at least one filter rule concerning at least one characteristic of each said content item, wherein said array comprises a content item bit string, and said each ordinal comprises a unique bit position in said content item bit string;
• (c) code for assigning to each user of said plurality of content items a user preference bit string, wherein each unique bit position in said user preference bit string indicates whether said user has a preference for a corresponding characteristic of said content items;
• (d) code for comparing said user preference bit string to each said content item bit string to determine if any characteristics match, wherein, in (d), said computer executable code includes code for performing a bitwise AND operation between each said content item bit string and said user preference bit string;
• (e) code for calculating for each said content item a relevance value in dependence upon said comparing in (d);
• (f) code for ordering said plurality of content items based, at least in part, on said relevance values calculated in (e).