Interpolation: 

Interpolation is a way angular use to display variables inside your HTML using the curly braces. You can display variables, named. Name <b>name<b> using {{name}} 

You can bind the data from the class to the template

1. Bind data using double curly bracket

{{property_name}} → there is class property name here. Then showing dynamic value. 

2. Using expression 

<h2>{{2+2}}</h2>  → output: 4

3. Also concatenation + property name 

concatenation: <p>{{“welcome ” + name}}</p>

<p>{{name.length}}</p>

<p>{{name.toUpperCase()}}</p>

4. Using method

<p>{{greetUser()}}</p>

5. Alternate way 

public siteUrl = window.location.href;

<p>{{siteUrl}}</p>

Not possible: 

<p>{{a = 2+2}}</p> (You can not assign the expression in a variable. So assignment is not possible in a variable)

<p>{{window.location.href}}</p> (so template is not aware javascript global variable)