Photos are hard to sort and organize. You might think it best to organize the photos by who is in the picture, or maybe where the picture was taken. The photographer is often considered to be a good start. But then maybe you should sort by the type of photography if you are a photo geek - black-and-white, colour, digital, etc. Pretty soon you are overwhelmed by the possibilities - photos ranked by how much you like them, photos by topic, photos of cats...
Piwigo lets us organize photos however we would like, and make them readily searchable so we can find those long-lost photos of Uncle Benny at the lake. Photos can appear in more than one album or collection, so Uncle Benny might appear in an album about his father and mother and their descendants, and in an album about adventures at the lake, and in an album of all photos taken by Aunt Mildred, and an album of photos cousin Jimmy thinks are cool.
How things are currently arranged
Most of the photos are very generally organized by time.
There is a "master collection" of photo albums organized by century/decade/year which the administrators use to sort the larger collection. This collection of albums is not public because it is supposed to have every photo on the site in it. Each family surname also has a timeline collection of albums, and photos relevant to each family are organized into these so everyone in each family may look at their family's collection of photos over time.
Base family name
Family collections usually have a 'base' album which is just the family name. Generally few photos are added to this base album, and instead other albums are added here. The types of photos which might end up in the base are collective photos such as family reunion photos, multi-generational photos including the ever-popular '5 generations' groups, and photos of family matriarchs/patriarchs.
Each family also has a 'caddie' album. Photographers used to sort photos into caddies, and then into the appropriate albums or envelopes, so the photos in the caddie are ones which we do not know when they were taken, or perhaps we don't know who the subject is or the photographer. Think of the caddie as the 'inbox', and if you have some information about photos you find there please make a comment! you may be able to get the image identified and properly sorted.
Timelines and Events
Timelines are collections of albums which organize photos over time in an easy to browse fashion. When the date a photo was taken is known it is easy to sort it chronologically, but often we do not have precise information and can only deduce the year, or even only the decade. Piwigo will automagically sort images when the digital image includes the creation date - you can see this in action at the calendar. But you can also immediately see that there are errors with this method of sorting: scans of images from the last century may have a creation date of today, and other images without dates may be sorted to the first day of year 0. For this reason we make a hierarchy of photo albums organized by time:
...and so on. We generally create albums as they are needed, so if we find proof that the image of Isaac Elliot Dickson and children is, as we think, from 1886, we will need to create the albums 80s and 1886 in the 1800s album, and add the photo there. Until we have evidence, though, it just resides in the 1800s album.
Sometimes there are events when a lot of photos are taken. For example, in 1987 a number of photos were taken at the Alubuquerque Balloon Festival, so we could make an album about just that event. Usually such albums are created about family events, like a wedding or a graduation, so such albums might only be available for members of the family to view. An event album is usually added to the year when the event took place.
Modern phones can include a photo's location as determined by the phone's gps receiver into the photo as it is taken. Or the location can be later added to the image in some photo editing software. Our gallery software can read this EXIF data and display images on a map. However, if an image is missing this location data an editor can still add the location where the image was taken, or the location of the image subject, to the photo. This is particularly impressive in the full-screen map display.
This can allow visitors to search for photos by their physical location - but be aware that very few photos in the gallery have this kind of information available. You simply will not see most of the photos if you only search using the maps.
Metadata, or "tags"
Each image can have many bits of information added to it, which are used by the search engine when looking for images. You can refine searches by looking for photos with more than one tag, for example a photo with both Wayne Saewyc and Elizabeth Saewyc, or perhaps Wayne Saewyc and Norse Lady to find pictures of me on my little sailboat. Tags are not quite the same as albums, but they can be used to temporarily create albums and collections. Usually the three things each photo can be tagged with are the subject(s), the location, and the year the image was taken. Even if you know only one of these three things that will help someone in the future trying to find the image you are adding to the gallery.
This is where you can get very creative - look for 'Toddler', or 'Age 6', or 'Kitsap'. Maybe birthday cake is important in the image; add that! you don't know what your future self may be looking for when you come back to find a photo.
Anything is possible. Photos are organized this way now, 2015, but they can be reorganized in better ways by some other family member. If things do change, hopefully we will remember to update this little essay to explain the new situation. Hopefully this will also help you find things you may be looking for now, or give you good ideas on where to put things for the moment.