1. A natural language tagging system for processing electronic files on a user's computing system, wherein the natural language tagging system is embodied in one or more non-transitory computer accessible storage media and comprises instructions executable by a processor to: observe tagging of an electronic file by a user on the computing system, the user tagging producing a user-tagged electronic file; associate a user-created natural language query with a tag of the user-tagged electronic file, wherein the user-created natural language query is received via a user interface of the computing system and relates to a plurality of electronic files stored on the computing system; execute the natural language query on the plurality of electronic files stored on the computing system; compute a similarity between each of one or more untagged electronic files included in a search result for the executed natural language query; in an automated fashion, tag an untagged electronic file of the one or more untagged electronic files in the search result with a tag comprising at least a portion of the natural language query; wherein the natural language tagging system determines a folder name of a folder storing each of the one or more untagged electronic files on the computing system, wherein, in an automated fashion, the natural language tagging system propagates at least a portion of the folder name as a part of the tag for each of the one or more untagged electronic files stored in the folder, and wherein the system determines a frequent word contained in each of the one or more untagged electronic files stored in the folder and propagates the folder name as the part of the tag for the one or more untagged electronic files stored in the folder only if the folder name matches the frequent word.