Different type of validation for HTML5:

1. Required Attribute: It is used when the value before submission of a form in not filled.
It is sometimes known as Mandatory or Compulsory field.

Use of "required" attribute.
Example:

<form action="" method="post">
    Name:<br>
    <input type="text" name="name" required>
    <br>
    Age:<br>
    <input type="text" name="age" required><br>
    Email:<br><input type="email" name="email" required placeholder="Enter a valid email address"><br>
    Website:<br><input type="url" name="website" required pattern="https?://.+"><br>
    <input type="submit" />
    </form><br>

2. Readonly Attribute: it specifies that an input field is read-only and it cannot be modified.

Use of "readonly" attribute.
Example:

<form action="" method="post">
        Name:<br>
        <input type="text" name="name" value="sid" readonly>
        <br>
        Age:<br>
        <input type="text" name="age" required><br>
        <input type="submit" />
  </form><br>

3. Disabled Attribute: It is unusable and un-clickable. It specifies that the input field should be disabled.

Use of "disabled" attribute.
Example:

 <form action="" method="post">
            Name:<br>
            <input type="text" name="name" value="sid" disabled>
            <br>
            Age:<br>
            <input type="text" name="age" required><br>
            <input type="submit" />
    </form><br>

4. Maxlength Attribute: It specifies the maximum number of characters allowed in the input field.

Use of "maxlength" attribute.
Example:

 <form action="" method="post">
                Name:<br>
                <input type="text" name="name" maxlength="10">
                <br>
                Age:<br>
                <input type="text" name="age" required><br>
                <input type="submit" />
        </form>

5. Pattern Attribute: It specifies a regular expression that the input field value is checked against.

Use of "pattern" attribute.
Example:

 <form action="" method="post">
                Name:<br>
                <input type="text" name="countryCode" pattern="[A-Za-z]{3}" title="Only three letter country code">
                <br>
                <input type="submit" />
        </form><br>

6. Multiple Attribute: It specifies that the user is allowed to enter more than one value in the input field.

Use of "multiple" attribute.
Example:

 <form action="" method="post">
                    Select images: <br><input type="file" name="img" multiple>
                    <br>
                    <input type="submit" />
            </form>