mat hint
snippet in html

angular material input

user5620

Html
<form class="example-form">
  <mat-form-field class="example-full-width">
    <mat-label>Favorite food</mat-label>
    <input matInput placeholder="Ex. Pizza" value="Sushi">
  </mat-form-field>

  <mat-form-field class="example-full-width">
    <mat-label>Leave a comment</mat-label>
    <textarea matInput placeholder="Ex. It makes me feel...">

mat hint

user8120

<mat-form-field appearance="standard">
    <mat-label>Standard form field</mat-label>
    <input matInput placeholder="Placeholder">
    <mat-icon matSuffix>sentiment_very_satisfied</mat-icon>
    <mat-hint>Hint</mat-hint>
</mat-form-field>