A couple of comments on features

The element contains two child elements: ElementManifests and ActivationDependencies. The ElementManifests element supports one or more ElementManifest and ElementFile elements. The ElementManifest and ElementFile elements are used to reference files that make up the feature.

The great thing about referencing files from the feature.xml file is that you don't need to specify them directly in the manifest.xml file. SharePoint automatically deploys these files when it deploys the feature.xml file that references them. Here is how it works. SharePoint reads the value of the Location attribute on the and ElementFile elements, which are nothing but the folder paths to the referenced files. SharePoint then creates the same folder structure in the root folder of the feature in the file system of every WFE server and deploys the referenced files to the respective folder.

For example, consider the following:

The above feature deploys two Web parts to SharePoint. The ElementManifest elements reference the Elements1.xml and Elements2.xml element manifest files that provision the Web parts into the Web parts gallery. The ElementFile elements reference the WebPart1.webpart and WebPart2.webpart files that contain the definitions for these two Web parts.

The only thing that you need to reference in the manifest.xml file is the feature itself. No need to reference the element manifest files that contain the Web part provisioning logic or Web part definition files:

SharePoint will read the values of the Location attributes on two ElementManifest elements and create two folders named WebPart1 and WebPart2 in the root folder of the feature on every WFE server in the server farm and deploy the Elements1.xml and Elements2.xml element manifest files into these two folders, respectively.

SharePoint will also read the values of the Location attributes on two ElementFile elements. Because the WebPart1 and WebPart2 folders are already created in the root folder of the feature, SharePoint simply deploys the WebPart1.webpart and WebPart2.webpart Web part definition files into these folders, respectively.

So far I covered the ElementManifests child element of the Feature element. Next I'll discuss the ActivationDependencies child element. This child element can contain zero or more ActivationDependency element. Each ActivationDependency element specifies a feature that has to be activated before the current feature can be activated. In other words, the activation of the current feature depends on the activation of the features referenced in the ActivationDependencies element.

Does this mean that SharePoint automatically activates the features on which the activation of the current feature depends? The answer is it depends on whether the features on which the activation of the current feature depends are hidden or not.

If the dependent features are hidden and inactive, SharePoint automatically activates them. This also means that SharePoint automatically deactivates these hidden features when the last feature that depends on them is deactivated.

However, if the dependent features are visible, SharePoint does not automatically activate them. This means that these features must be activated before an attempt is made to activate the current feature otherwise the current feature will not be activated.