From W3C Wiki
The <embed> element represents an integration point for an external (typically non-HTML) application or interactive content.
Authors should ensure that the information and user interface components must be presentable to users in ways they can perceive (WCAG 2.0 - Principle 1: Perceivable). This includes providing alternatives for time-based media Guideline 1.2.
src= URL potentially surrounded by spaces
gives the address of the resource being embedded.
type= MIME type
Specifies the type of the resource.
width= non-negative integer
Give the width of the visual content of the element, in CSS pixels.
height= non-negative integer
Give the height of the visual content of the element, in CSS pixels.
Here's a way to embed a resource that requires a proprietary plug-in, like Flash.
To pass the plugin a parameter "quality" with the value "high", an attribute can be specified: [try it]:
<embed src="catgame.swf" quality="high">
This would be equivalent to the following, when using an object element instead:
<object data="catgame.swf"> <param name="quality" value="high"> </object>
The HTML5 specification defines the <embed> element in 4.8.3 The embed element.