Introduction to How Photo Sharing Works
Do you have lots of dusty photo albums with pages full of old photos? Thanks to the many free photo-sharing Web sites currently available, those are a thing of the past. Instead of carrying your photos around when you want to share them, you can now easily share them from your computer.
Now it only takes a few minutes to upload a batch of digital photos and e-mail friends and family who might want to see them. For a price and a little extra effort, you can print out those same digital pictures on quality photo stock for permanent keepsakes, or get photo-sharing sites to mail them to you.
Photo album with old pictures
Image courtesy ImageAfter
You can scan in all of these images, upload them to a photo sharing Web site and share them with anybody you choose.
Photo-sharing sites offer many features, and there are several of them on the Web. Most are free but offer additional storage space, bandwidth and/or other features for a price. We'll use Flickr as an example because it's one of the most popular photo-sharing Web sites, but there are many other great sites on the Internet that offer similar features.
Flickr homepage
Flickr is a popular photo-sharing Web site.
The most basic feature is the ability to upload your digital photos to the Web, organize them and allow other people to see them. The first step is uploading. The upload page of most sharing sites will have a box with a "Browse" button. Clicking on "Browse" allows you to find the files on your hard drive. Usually, there are several boxes on the page, so you can find multiple photos and upload them all at once. It may take several minutes for the upload to finish, depending on how many photos you've chosen and how large the files are. Some photo-sharing sites have programs that you can download to your desktop and use to upload photos to the site. Flickr also has ways to upload images via e-mail and certain types of cell phones with cameras.
Flickr upload page
A basic upload page lets you browse your hard drive and upload images to the site.
At this point, some sites will automatically resize your photos. Usually the photo size is reduced to keep the site's bandwidth and storage space use minimized. Keeping photos at the original size may be an option for paying members.
Categorizing
Once you upload the photos, you can categorize them, arrange them into sets and give them descriptions. The manner of organizing the photos depends on the site. Some use tags, which are keywords that you can assign to each photo. When someone wants to look at your photos, they can see a list of your tags and choose to look at all your photos with certain keywords. If they only wanted to see photos of horses that you took while on vacation, they could combine the tags "horse" and "vacation." Often, the list of tags will show which categories hold the most photos by showing that tag in a larger font size.
Exploring Flickr through tags
You can search through popular tags, sets of photos and groups of photos that follow specific themes.
Alternately, you can arrange photos into sets. You can set the specific order of the photos, so visitors to your sharing site will see them like a slideshow (some sites have an actual slideshow viewing option).
Viewing all images tagged with 'vacation' using the slideshow feature on Flickr
Viewing all images tagged with "vacation" using the
slideshow feature.

The descriptions on each photo can include as much information as you like. The camera used, the location of the photo, the subject of the photo, or any interesting stories about the photograph are all possible in the description.
Most digital cameras encode information about the photo and the camera itself into the image files. This is EXIF data (Exchangeable Image File Format), and when you upload your photos to a site, this information can be included automatically. This will allow users to see what camera you used, the time and date the photo was taken and the camera settings used for the photo, all without you having to enter any of the data yourself. Of course, you can disable this if you don't want people to know it.
When you upload your photos to a photo-sharing site, you aren't necessarily putting them out there for the entire world to see (although you can). It is possible to set permissions on each photo. Anyone can view photos set to "public." Set a photo to "private" and it will only display for people who you allow to see it. On some sites, the "private" category covers everyone on your contacts or friends list. You can also create different categories of people, and only allow certain categories of them to see certain photos. You might want anyone you know to see your nature pictures, but you don't want your co-workers see the photos you took at your family reunion. So you can put the co-workers in their own category and exclude them from those pictures.
Flickr's page where you can allow/disallow downloads
You can decide who can (and who can't) download your images.
Finally, you can disable downloading on some or all of your photos. This prevents people from saving the photo to their own computer. However, technically speaking, if an image is displayed on someone's computer, they can find a way to download it. Flickr puts a transparent image over your photo to hinder downloading, but it can't stop people completely from downloading.
Printing
Photo-sharing sites usually provide an option to order physical prints of your photos. A third party might provide the service, or the sharing site itself might provide it. Depending on which site you're using, many options are available. You can have the photos shipped directly to your house, though you might have to pay shipping costs. Some sites affiliate with "brick and mortar" stores. You can find a location close to where you live, and you can just drop by the store to pick up your photos.
Choosing the order prints option on Flickr
With many sites, you have the option of ordering different sizes of prints. You can even get your image printed on stamps or posters.
Other options allow you to customize your photos before they are printed. Add a border to give the photo an easy matte, or insert some text and clip art and make your own Christmas cards. There's also a wide range or prices for digital photo printing. Many sites offer special deals with prices as low as six cents per print, or a certain number of free prints when you first create your account. Regular prices generally fall in the 12 to 20 cents per print range.
Premium Memberships
While most photo-sharing sites are free, many also offer premium memberships for a monthly or annual fee. This opens up more advanced features for users and removes some of the limits placed on free users. For example, sites may limit the upload bandwidth of free users. Premium members will have either no limits, or much higher limits. Premium members also view the site ad-free, while pages viewed by free users may have banner ads on them. Access to full-size, full-resolution versions of images may be restricted to premium members as well, and they may have their own personal URL on the site (such ashttp://www.photosite.com/edsphotos or http://edsphotos.photosite.com). The exact features available to paying site members depends on the site.
Buying a Pro Account on Flickr
On Flickr, premium memberships are called "Pro Accounts." 
Community
Photo-sharing sites offer more than convenience and commerce. Many of them are also online communities of photographers, both amateur and professional. Some sites are more conducive to the community aspect than others are, allowing users to form groups, keep contact lists and comment on each other's photos. This allows people to share photography tips, find others with similar interests and get in touch with photographers from around the world. It also levels the playing field – if you take a beautiful photo with a $60 digital camera, it will be praised just as highly as one taken with a $1,500 pro camera and processed with expensive software.
The Flickr group 'Waterfalls Around the World'
Many sites have groups that you can join to share your photos and comment on others. This group is for photos of waterfalls.
Instead of photo-sharing sites with community features, many community Web sites also allow users to share photos. MySpace and friendster are two examples. Since the emphasis at these sites is not on photography, their photo organizing and sharing features are not as robust.
For many people, Web sites like Flickr make sharing photos much easier. Instead of having to catalog prints in an album and carry it around to share with friends and family, you can point them to your account on a photo sharing Web site. And if you still like having tangible copies of those images, you can always order prints later.