There are two broad types of change that can be made within Salesforce:
In this article we'll focus on declarative changes, what they are, and how they are made.
What is a declarative change?
Salesforce have a motto of "clicks not code" when it comes to development on the platform. This encourages users to minimize code use and instead make changes through the platform UI.
These kinds of changes are known as declarative changes, and they form the mainstay of many users customisation of their orgs.
The benefits of declarative development
By allowing users to make changes without writing code, Salesforce allows anyone to begin customising the platform even if they don't have a software development background.
This opens up the platform to a much wider user base and encourages many more users to get involved with development. This approach of encouraging "citizen developers" is one of the big draws of the Salesforce platform over other traditional CRMs and it allows companies to develop new features and respond to change faster than would traditionally be possible.
How declarative changes are made
All declarative changes are made via the UI in an org. They can be as simple as clicking a button to enable a feature, and as complex as building workflows to automate entire processes.
A few examples of the sorts of change that can be made declaratively:
Adding a new custom field to the Account object
Changing a page layout to control how a page displays to a user
Editing a permission set to control which users can view a field
Adding a new value set value
Want to know more?
You can learn more about declarative changes in the excellent Salesforce Trailhead modules for admins here.