The platform itself defines one perspective, the Resource perspective. Other platform plug-ins, such as the help system and the Java tooling, define additional perspectives. Your plug-in can define its own perspective by contributing to the org.eclipse.ui.perspectives extension point.
The specification of the perspective in the plugin.xml is straightforward. The following markup is used by the workbench in defining its own resource perspective.
<extension
point="org.eclipse.ui.perspectives">
<perspective
name="%Perspective.resourcePerspective"
icon="icons/full/cview16/resource_persp.png"
class="org.eclipse.ui.internal.ResourcePerspective"
id="org.eclipse.ui.resourcePerspective">
</perspective>
</extension>
A plug-in must supply an id and name for the perspective, along with the name of the class that implements the perspective. An icon can also be specified. The perspective class should implement IPerspectiveFactory.