vBulletin Manual - Terminology

It is important that you understand some of the basic terms used by Project Tools.

Project – this is the general organizational unit in Project Tools. Each project should represent a collection of items that need to be completed to allow something to come to fruition. A project can cover anything you wish, from developing a piece of software to building a car.
Issue – the basic unit of a project. An issue is a specific item that needs to be completed. A project would contain many issues. An issue can cover anything you want, though you may want to define your own issue types to make the issue "fit".
Tag – a tag is a form of meta-data to enable structured searching on data that can’t easily be represented otherwise. You may define any tags you wish. Common uses include creating tags for the topics the issue covers. Alternatively, tags could represent actions that need to be taken for issues to be completed, such as reviews being made.
Issue Type – an issue type is a way of grouping issues within a project. All issues must be assigned to an issue type. An issue type allows use of specific phrases ("Post New Bug") and specific statuses ("Fixed") for issues of that type. Additionally, permissions are definable per issue type.
Issue Status – an issue status simply describes the progress of the issue. These are specified per issue type.
Petition – petitions allow users to request that an issue’s status be changed. This is useful to draw attention to an issue with a resolution that may not be correct. A developer may assume a bug is fixed, but it may not fix the issue for a user. This user could submit a petition to change the status back to "Confirmed".

These terms are discussed in more detail in the appropriate sections.