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Chapter 1: Introduction

1.1. About SVG

This specification defines the features and syntax forScalable Vector Graphics (SVG).

SVG is a language for describing two-dimensional graphics.As a standalone format or when mixed with other XML, it uses theXML syntax [xml].SVG code used inside HTML documents uses the HTML syntax [HTML].SVG allows for three types of graphic objects: vector graphicshapes (e.g., paths consisting of straight lines and curves),images and text. Graphical objects can be grouped, styled,transformed and composited.The feature set includes nested transformations, clippingpaths, alpha masks, filter effects and template objects.

SVG drawings can beinteractiveanddynamic.Animationscan be defined and triggeredeither declaratively (i.e., by embedding SVG animation elementsin SVG content) or via scripting.

Sophisticated applications of SVG are possible by use of asupplemental scripting language which accessesSVG Document Object Model (DOM), whichprovides complete access to all elements, attributes andproperties. A rich set ofevent handlerscan be assigned to any SVG graphical object.Within a web page, the same scripts can work on both HTML and SVG elements.Scripting.

SVG is useful for rich graphical presentation of information, including a numberofaccessibility features that, used correctly,ensure the content can be used by the widest possible audience. But a directlink to source data, where possible,is helpful for many people to understand the content provided.

1.2. Compatibility with other standards efforts

SVG leverages and integrates with other W3C specificationsand standards efforts, as described in the following:

• SVG can be integrated withHTML either by using SVG in HTML or by using HTML in SVG, in both cases either by inclusion or reference.
• SVG is an application of XML and is compatible withXML 1.0 and with theNamespaces in XML specification. However, when SVG content is included in HTML document, the HTML syntax applies and may not be compatible with XML. SeeSVG Integration for details.
• SVG content is styled with CSS. SeeStyling with CSS for details.
• SVG includes a complete Document Object Model (DOM) and extendsDOM4. The SVG DOM has a high level of compatibility and consistency with the HTML DOM. Additionally, the SVG DOM supports and incorporates many of the facilities described in the CSS object model and event handling [dom-level-2-style] [uievents].
• SVG incorporates some features and approaches that are part ofSMIL 3, including the‘switch’ element and the‘systemLanguage’ attribute.
• SVG is compatible with W3C work on internationalization. References (W3C and otherwise) include: [UNICODE] and [charmod].
• SVG is compatible withW3C work on Web Accessibility. SeeAccessibility Support.

1.3. Normative Terminology

Within this specification, the key words "MUST", "MUST NOT","REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT","RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted asdescribed inKey words for use in RFCs to Indicate Requirement Levels[rfc2119].However, for readability, these words do not appear in alluppercase letters in this specification.

At times, this specification recommends good practice forauthors and user agents.