A VectorDrawable should consist of at least one <path> tag defining a shape

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="24dp"
    android:height="24dp"
    android:viewportWidth="24.0"
    android:viewportHeight="24.0">
    <path
        android:fillColor="#FF000000"
        android:pathData="M0,24 l12,-24 l12,24 z"/>
</vector>

This would produce a black triangle:

A <clip-path> defines a shape which acts as a window, only allowing parts of a <path> to show if they are within the <clip-path> shape and cutting off the rest.

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:width="24dp"
    android:height="24dp"
    android:viewportWidth="24.0"
    android:viewportHeight="24.0">
    <clip-path
        android:name="square clip path"
        android:pathData="M6,6 h12 v12 h-12 z"/>
    <path
        android:name="triangle"
        android:fillColor="#FF000000"
        android:pathData="M0,24 l12,-24 l12,24 z"/>

</vector>

In this case the <path> produces a black triangle, but the <clip-path> defines a smaller square shape, only allowing part of the triangle to show through:

A <group> tag allows the scaling, rotation, and position of one or more elements of a VectorDrawable to be adjusted:

<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="24dp"
android:height="24dp"
android:viewportWidth="24.0"
android:viewportHeight="24.0">
    <path
        android:pathData="M0,0 h4 v4 h-4 z"
        android:fillColor="#FF000000"/>

    <group
        android:name="middle square group"
        android:translateX="10"
        android:translateY="10"
        android:rotation="45">
        <path
            android:pathData="M0,0 h4 v4 h-4 z"
            android:fillColor="#FF000000"/>
    </group>

    <group
        android:name="last square group"
        android:translateX="18"
        android:translateY="18"
        android:scaleX="1.5">
        <path
            android:pathData="M0,0 h4 v4 h-4 z"
            android:fillColor="#FF000000"/>
    </group>
</vector>

The example code above contains three identical <path> tags, all describing black squares. The first square is unadjusted. The second square is wrapped in a <group> tag which moves it and rotates it by 45°. The third square is wrapped in a <group> tag which moves it and stretches it horizontally by 50%. The result is as follows:

A <group> tag can contain multiple <path> and <clip-path> tags. It can even contain another <group>.

An AnimatedVectorDrawable requires at least 3 components:

• A VectorDrawable which will be manipulated
• An objectAnimator which defines what property to change and how
• The AnimatedVectorDrawable itself which connects the objectAnimator to the VectorDrawable to create the animation

The following creates a triangle that transitions its color from black to red.

The VectorDrawable, filename: triangle_vector_drawable.xml

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="24dp"
    android:height="24dp"
    android:viewportWidth="24.0"
    android:viewportHeight="24.0">

    <path
        android:name="triangle"
        android:fillColor="@android:color/black"
        android:pathData="M0,24 l12,-24 l12,24 z"/>

</vector>

The objectAnimator, filename: color_change_animator.xml

<objectAnimator xmlns:android="http://schemas.android.com/apk/res/android"
    android:propertyName="fillColor"
    android:duration="2000"
    android:repeatCount="infinite"
    android:valueFrom="@android:color/black"
    android:valueTo="@android:color/holo_red_light"/>

The AnimatedVectorDrawable, filename: triangle_animated_vector.xml

<animated-vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:drawable="@drawable/triangle_vector_drawable">

    <target
        android:animation="@animator/color_change_animator"
        android:name="triangle"/>

</animated-vector>

Note that the <target> specifies android:name="triangle" which matches the <path> in the VectorDrawable. A VectorDrawable may contain multiple elements and the android:name property is used to define which element is being targeted.

Result:

Using SVG stroke makes it easier to create a Vector drawable with unified stroke length, as per Material Design guidelines:

Consistent stroke weights are key to unifying the overall system icon family. Maintain a 2dp width for all stroke instances, including curves, angles, and both interior and exterior strokes.

So, for example, this is how you would create a "plus" sign using strokes:

<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="24dp"
android:height="24dp"
android:viewportHeight="24.0"
android:viewportWidth="24.0">
    <path
        android:fillColor="#FF000000"
        android:strokeColor="#F000"
        android:strokeWidth="2"
        android:pathData="M12,0 V24 M0,12 H24" />
</vector>

• strokeColor defines the color of the stroke.

• strokeWidth defines the width (in dp) of the stroke (2dp in this case, as suggested by the guidelines).

• pathData is where we describe our SVG image:

• M12,0 moves the "cursor" to the position 12,0

• V24 creates a vertical line to the position 12, 24

etc., see SVG documentation and this useful "SVG Path" tutorial from w3schools to learn more about the specific path commands.

As a result, we got this no-frills plus sign:

This is especially useful for creating an AnimatedVectorDrawable, since you are now operating with a single stroke with an unified length, instead of an otherwise complicated path.

A few pre-requisites in the build.gradle for vectors to work all the way down to API 7 for VectorDrawables and API 13 for AnimatedVectorDrawables (with some caveats currently):

//Build Tools has to be 24+
buildToolsVersion '24.0.0'

defaultConfig {
    vectorDrawables.useSupportLibrary = true
    generatedDensities = []
    aaptOptions {
        additionalParameters "--no-version-vectors"
    }
}

dependencies {
    compile 'com.android.support:appcompat-v7:24.1.1'
}

In your layout.xml:

<ImageView
    android:id="@+id/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    appCompat:src="@drawable/vector_drawable"
    android:contentDescription="@null" />