In archival science, a fonds is the aggregation of documents that originate from the same source. More specifically, a fonds distinguishes itself from a collection through its organic nature, as archival documents that have been naturally accumulated (made or received) by an individual, company, institution, etc. as a byproduct of business or day-to-day activities.
In modern archival practice, the fonds is generally the highest level of arrangement, and is usually used to describe the whole of the archives of an organisation or the papers of an individual. It may be divided into sub-fonds, generally the records of different branches of an organisation or major themes within the papers of an individual. These are in turn further subdivided into series (which may in a smaller archive come directly below a fonds without the presence of a sub-fonds), usually used for groupings of individual types of documents (minutes, correspondence files, deeds, etc.), sub-series, files, and items. An item is the smallest archival unit, and is usually physically indivisible (a single volume or letter, for instance). It is technically possible to add an infinite number of subs to the fonds, series or file, but in practice it is actually rare for more than one to be used.
The term fonds originated in French archival practice, but has now spread to English-speaking countries as well. In some countries, including the United Kingdom, Australia and Canada, it has officially replaced the misleading term collection, which used to be used for this level and is now only used for document aggregations assembled, but not created, by a collector. In the United States, archivists still often use the terms "collection" and "record group" for comparable levels of archival materials.