1 page.title=Building Apps with Contacts & Sign-In 2 page.trainingcourse=true 3 4 @jd:body 5 6 7 <p>These lessons teach you how to include contact information and authenticate users with the same 8 credentials they use for Google. These features allow your app to connect users with people they 9 care about and provide a personalized experience without creating new user accounts.</p> 10
