share the same state of a service only between a Parent and its Child components angular code example

Example: input property angular

//passing properties to child elements
<app-slider [title]="'This is a title'"> </app-slider>

//inside the component slider i add just before the constructor :
.
.
@input() title: string;
constructor(){
}


//after this we can use these new property inside the .html file of the component
<div id='slider' class='slider-big'>
  <h1> {{title}}</h1>

</div>