XBRL
an XML-based technology standard that improves the way information is created, processed, distributed and analyzed by using “tags” that package information such as definitions, labels, references and time period around individual numbers or text.

Taxonomy
a dictionary of terms used to describe a particular reporting situation such as the XBRL US GAAP line items which include terms such as net income, EPS, cash, etc.  Each term has specific attributes that help define it including label and definition and potentially references.

An XBRL taxonomy can also be defined as an electronic description and classification system for the contents of financial statements and other business reporting documents. Taxonomies may represent hundreds or even thousands of individual business reporting concepts, mathematical and definitional relationships among them, along with text labels in multiple languages, references to authoritative literature, and information about how to display each concept to a user. (Source: XBRL International)

Tags
individual elements within a taxonomy, e.g., net income.

Example
Assume that a company released its 10K with XBRL. One example of a XBRL tag is “usfr-pte:NetIncome.” This is the tag that a company would attach to its US GAAP net income figure on its income statement.

Dimension
a tool in the XBRL standard that allows preparers to leverage XBRL tags to create simple tables and more complex pivot-style tables within financial statements, e.g., to define segment data.

Extension
a company-defined line item that is not available in the current taxonomy.  Preparers have the ability to create new custom terms if they have a very unique reporting situation that is not available in the taxonomy terms. An XBRL extension is a taxonomy that extends an existing base taxonomy. The extension taxonomy may include, exclude or change information from the base taxonomy. The extension can be regarded as an overlay which modifies the structure of the taxonomy, adds and prohibits elements, their labels, linking, order of appearance and other characteristics. The main idea behind an extension is to encourage business users to tailor the taxonomy to their specific needs, while using the elements of the base taxonomy to ensure comparability.

Example
For example if you include revenues for various products in the income statement but the standard taxonomy only includes an element called Other Revenue you should add these new revenue tags as children of Other Revenue that could be rolled up into Other Revenue for comparability.

Instance Document
an XBRL-enabled document, e.g., income statement from ABC company. XBRL Instances contain the reported data with their values and "contexts" (e.g. currency or reporting period). Instances must be linked to at least one taxonomy which define their contexts, labels or references.

Labels
if an element already exists within the standard taxonomy that can be used to represent your information but you do not like the standard label, do not add an additional element, just change the label.

Schema
XBRL Schemas together with linkbases define an XBRL taxonomy. The purpose of XBRL schemas is to define taxonomy elements (concepts) and give each concept a name and define its characteristics. It can be regarded as a container where elements and references to “linkbase” files are defined.

Linkbase
XBRL linkbases and XBRL Schemas define together an XBRL taxonomy. Taxonomies with only the core elements (concepts) defined in an XBRL Schema would be useless. The purpose of XBRL linkbases is to combine labels and references to the concepts as well as define relationships between those concepts.

There are five different kinds of linkbases. Each has a special purpose: