Adobe Lightroom Classic has two types of collections... one is simply referred to as Collection and the other Smart Collection. Perhaps a better way of looking at these is: "Dumb" Collection and Smart Collection.
The "Dumb" Collection doesn't do much other than provide a place for you to collect some photos. Photos are placed in such a Collection by drag and drop methods.
The Smart Collections gather photos for you automatically based on rules that you create. If you have ever used a computer spreadsheet program, you are already familiar with the concept of Smart Collections. The formulae that you would enter into a spreadsheet cell is analogous to the rules that you create for a Smart Collection.
For instance, if you were to create a Smart Collection entitled "Grand Teton National Park" with the rule that the photo has the "Grand-Teton-National-Park" Keyword assigned to it, this Smart Collection would contain all of the photos you assigned that Keyword to. If you assign that Keyword to another photo, it will automatically be added to the Smart Collection. Conversely, if you were to remove that Keyword from a photo, it will automatically be removed from the Smart Collection.
Creating a Smart Collection
To create a Smart Collection, one clicks on the plus (+) sign next to the word Collection in the Collections panel on the left hand side of the Lightroom Classic Library module. You must be in the Library module. From the drop down menu, click on the "Create a Smart Collection" option. You will be presentation with a template form that allows you to build your Smart Collection.
Let's use the following as a simple example: you want a Smart Collection to gather all of the photos that were:
a. Taken in Grand Teton National Park, and
b. They were the best photos (i.e., five-star) you have ever taken there.
Assuming you assigned Keywords to your photos and had assigned the Keyword "Grand-Teton-National-Park" to some number of your photos, you can set that up as your first rule in the Smart Collection template form.
1. Click on "Rating" to get a drop down menu. From that menu, select "Other Metadata", then "Keywords".
2. In the second column, you will see "Contains". This means that whatever Keyword you type into the third column, the Smart Collection will search through all of the Keywords of all of the photos you have taken and only provide those that contain that Keyword.
3. In the third column, type "Grand-Teton-National-Park"
4. In the Smart Collection template form, click the plus (+) sign next to the third column. You will be presented with another line or rule. The Rating presented is what you want. The "Is Greater Than or Equal To" presented is what you want. Now click on 5 stars.
5. You will notice at the top of the form "Match All of the Following Rules". For the result you are seeking, a photo must meet both of your rules to be included in this Smart Collection so this is what you want here.
6. Give this Smart Collection a name such as "Grand Teton NP - 5 Star Photos" and then click the "Create" button.
Lightroom Classic will then display the number of photos that meet the rules you have just setup.
How Do I use Smart Collections
I use Smart Collections in two ways. One use is to gather photos for use on my web site as described on the previous slide. The second use helps in my Workflow. This second use will be discussed in more detail starting with the "Keyword Location & Subject" slide.
Note: Smart Collections can include rules which allow for more sophisticated searches. Search for more details on the Internet to learn how you might do this.
This completes a brief introduction to Smart Collections. They required a fair amount of work to design and test but once that they are complete, they just work!