Similar to Protractors Locators we can also make use of Protractor CSS Expression as a means of finding an element on a web page. Once found on said web page we can also interact with them. CSS Expression behave very similarly to WebDriver CSS locator. In other words the CSS Expression help to locate an element on a web page by looking through the cascading style sheets of a given web page.
Protractor CSS Expression Video Tutorial
Follow this video tutorial to learn more about using CSS Expression to help identify an element on a web page and then interact with them.