Скачать или смотреть What is string interpolation in Angular ?

String Interpolation in Angular is a one-way data-binding technique that is used to transfer the data from a TypeScript code to an HTML template (view). 
These template expressions are enclosed within double curly braces i.e. {{ }}.
{{ component_property }}
String interpolation in Angular refers to a special type of syntax that makes use of template expressions in order to display the component data.
These template expressions are enclosed within double curly braces i.e. {{ }}.
The JavaScript expressions that are to be executed by Angular are added within the curly braces and the corresponding output is embedded into the HTML code.
Typically, these expressions are updated and registered like watches as a part of the digest cycle.