Before photographs were digital they were hard copy, some were in color and older ones were black and white, and even older ones were a brown and white color called "sepia" tone. Lately my father has taken to mailing me random old photos out of his collection. He's paring down. The pictures are of anything and everything and sent for the most part without comment. I'm lucky on the oldest ones that date back to his medical schooling in Japan. Because photos were rare for him back then, as he was a poor student, he noted on the back the circumstances. One photo had a cryptic note, "Here is the suit you never saw because it was stolen." I wondered who he had mailed the photo with the note to, his mother perhaps? My mother? And what was the story about the suit?
I suggest if you have old photos you jot down on the back as much as you can remember about them. A few were developed on Kodak film and will at least give me a year the photo was taken. Most do not have that much information. By the time my son gets them, if he doesn't toss them out in frustration, there will be no one left who can identify a cousin or an aunt. The only people my son would recognize are my immediate family. Even then, my mother passed away years before he was born. I doubt he would even recognize her in every shot.
In addition to writing down the year, it's nice if you can write down who is in the photo with some sort of scheme to identify them. Something akin to "Left to right are. . . " or "Sitting in the chair is so and so, standing behind her are etc." One old photo I received had a nice line drawing of the photo on the front with the names of the people on the drawing. If you have an old school photo you might want to circle yourself and any friends your children might know. They probably won't have too much interest in anyone else even if you could identify them all.
In addition to writing what you can remember on the back, it's cool if you can organize them into a photo book for your kids. If you do that, rewrite what information you have on a caption card underneath each photo. Write clearly in block print, or better yet, print the captions off of a computer. If your handwriting is flowery or difficult to read, no one will be able to enjoy the photos after you are gone. It's one project that is really nice if you can do it while you still remember stuff. Doing it one photo at a time or 5 a week, can make it less overwhelming.
To organize the items, purchase a binder or album that is specifically designed to preserve old photos. Some inexpensive albums sold at dollar stores are actually not good for fragile old pieces. Some even very pretty albums are not carefully made. Look for "mylar" sleeves to protect old photos from pollution, fingerprints, and the natural oil from our skin which can affect antiques. Another fine material for storage is called "bioriented polypropylene." Either one is clear and neither one should ripple, dimple or pucker over time.
If you want to matte your photos on a dark background in lieu of plastic sleeves, it is still important to chose the right paper. Chose paper that is advertised as "acid free." Comic book collectors use it to store their vintage comics. You can also find it at a specialty photo shop, or on line if you use a search engine for "acid free paper." Acid-free board can trap migrating acids in paper and neutralize it. Buffered board is not recommended for use with photos. Even if you plan on framing an older photo for display, it's good to use an acid free board for the matte.
If you are really keen to preserve old photos you can buy a scanner, save them all to a computer and put the photos on a disc for family members. There is a certain charm to how fast this can be done. In addition you no longer have to worry about the actual photo, you can even toss it if you like. Lastly all the photos can be located in one place, on a certain computer. If you email the photos to yourself you can even save them in cyber space some place like google docs.
The downside to doing this is if you lose the disc or break it, you'll lose a whole lot of pictures at once. If the computer has a virus or dies and you didn't make a back up you will similarly lose everything. I have a friend who religiously backed up her computer as well as printed hard copies, but when Hurricane Katrina swept through New Orleans she lost her discs, hard copies and computer all at the same time. There's no way around everything. The worst thing about scanning photos to disc would be the speed at which technology is changing. If you devote a lot of hours to the project and next year something akin to iPod comes out, making CD's obsolete, you'll have to reformat all over again. Keeping the photos in order, in an album, is something you can do once and be done with it.
There is a middle road. You can pick just a small number of photos and work off of a theme. Take the themed photos and turn them into a disc for friends and family. Something like "our many vacations" or "Christmases at the farm." Chose a photo representative of each year, or each family member, what ever you like. The beauty of this system is that you can pick as few photos as you like, 20 or 30 only, and write a more lengthy explanation of what is going on in each picture. A narrative that tells the story of your family to anyone lucky enough to inherit the album.