What's true about Apex controllers?
lightning components use server-side Apex Controllers
What types of elements do you see in the XML markup for Aura components?
static HTML tags ; Aura component tags
For sending secure notifications, which API is your best bet?
Streaming API
Which Heroku service allows you to unify your Salesforce data with Postgres data?
Heroku Connect
Aside from Trailhead, where is the best place to learn more about Salesforce development?
Salesforce Developer portal