Archaeological research generates a lot of documentation. Even before a site is excavated there is either a contract or agreement, a request from a private or public entity, and or a written research proposal produced by an archaeological researcher. In this initial stage, and in response to it, background research is conducted, laws and regulations are consulted, and a plan of action (including a budget) is drawn up. All this planning generates documentation before any dirt is even touched.
Once on site, the archaeologists record every bit of information possible. Why? Because we get only one chance to dig a site. Once a site is dug it is gone -- it no longer exists (except for features that might be left in place in the ground). Archaeological sites are non-renewable resources.
Proper archaeological work therefore produces, as accurately and comprehensively as possible, a detailed descriptive picture of the excavation. This description is compiled as the site is excavated -- as it is, effectively, taken apart and removed (i.e., destroyed). We only get one chance to make this description complete.
While excavation is underway, the archaeological field crew recovers artifacts and locates features (perhaps walls, privies or wells, fire rings, etc.). The location and position of such finds are closely measured and recorded --and these actions are themselves, in turn, recorded in bag lists, feature number logs, etc. There are also many field sketches and maps drawn to show what has been discovered. Drawings also document for posterity the soil layers encountered while excavating (each of which represents a different time period or activity episode), and the associations between artifacts discovered at the site. Photographs and other imaging mediums (e.g., video, laser scans) are employed to document each stage of the exploration, and these activities too are themselves documented --for example in photo logs, GIS records, etc. And finally, from day one, before the first shovel full of dirt is made, until the last (after the site is back-filled), the field crew members working at the site rigorously and religiously record every step of their actions, all observations, and each working conclusion in a field notebook.
All this documentation is what is used to make sense of the site and its evidence once the site is finished and analysis has begun in the lab. Without the archaeological site documentation to accompany the artifacts, all you have is a bunch of objects 'lost in space'. You don't know where anything was found, nor what it was found next to, and you will never be able to decipher 'what' happened 'where', or 'why'. You can't identify activity areas nor changing behaviors over time. With maps, photographs, sketches, and notes you have archaeology and thus human history. Without them you have only treasure hunting or collecting. The artifacts become a set of objects stripped of cultural context with no way to reconstruct their role or purpose in the past.
The archaeological records are more important perhaps than the artifacts found at a site. On the other hand, archaeological records are themselves artifacts: Archaeological records are the 'artifacts' of the 'archaeological process'. They stand in for the archaeological site after the excavation is done when the site no longer exists.
Image caption: "Archaeological Remains of Benjamin Franklin's House" mapped by B. Bruce Powell and Jackson Ward Moore. Area C, NHPP-IND 2772, 11 Dec. 61. National Park Service. Independence National Historical Park Archives.