Recommended way to embed PDF in HTML?

This is quick, easy, to the point and doesn’t require any third-party script:

<embed src="http://example.com/the.pdf" width="500" height="375" 
 type="application/pdf">

UPDATE (2/3/2021)

Adobe now offers it’s own PDF Embed API.

UPDATE (1/2018):

The Chrome browser on Android no longer supports PDF embeds. You can get around this by using the Google Drive PDF viewer

<embed src="https://drive.google.com/viewerng/
viewer?embedded=true&url=http://example.com/the.pdf" width="500" height="375">