What ensures that content published in Sitecore is available on live sites?

The role of the Sitecore Publisher is crucial in ensuring that content created or edited within the Sitecore environment becomes available on live sites. When content authors make changes or add new content within Sitecore, the Publisher is responsible for transferring this content from the authoring environment to the live production environment where it can be viewed by end-users.

Publishing processes can vary in terms of scope, such as publishing a single item, a subtree of content, or the entire site, depending on the requirements. The Publisher manages this transition efficiently, ensuring that all necessary dependencies and relationships are considered so that the content presented on the live site is accurate and up-to-date.

In contrast, other options do not serve this specific function. The Sitecore Authorizer is focused on user permissions and access control, while the Sitecore User Manager deals with managing users and roles within the system. The Sitecore Alarm System does not relate to content publication; instead, it could be associated with monitoring or alerting functionalities. Hence, the Sitecore Publisher is the correct answer as it directly handles the publishing process critical for content availability on live sites.