A Toolbar widget is a customizable app bar placed at the top of an activity or fragment and contains various UI elements such as a title, navigation icon, menu items, and actions. It was introduced as a replacement for the older ActionBar, providing more flexibility and customization options.

• Toolbar is more flexible then ActionBar.
• It looks modern and follows new material design.
• Define it and place it just like any other widget anywhere in the parent layout.
• Any widget can be placed inside toolbar.
• Multiple toolbars can be defined.
• An application may choose to designate a Toolbar as the action bar for an Activity using the setActionBar() method.

import androidx.appcompat.app.AppCompatActivity
import androidx.appcompat.widget.Toolbar

class MainActivity : AppCompatActivity() {

    private lateinit var toolbar: Toolbar

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        toolbar = findViewById(R.id.toolbar)
        setSupportActionBar(toolbar)
        
        // Customize the toolbar as needed
        supportActionBar?.apply {
            title = "My Toolbar"
            // Additional customization options
        }
    }
}

  <?xml version="1.0" encoding="utf-8"? />
 <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="@color/colorPrimary"
        app:title="Example Toolbar"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

     <!-- Rest of layout -- >

 </androidx.constraintlayout.widget.ConstraintLayout>