Bitmap image formats for the web—GIF, JPEG, WBMP, and PNG—describe images using a grid of pixels. The resulting files tend to be bulky, limited to a single (often low) resolution, and consume large amounts of bandwidth on the web. SVG, on the other hand, is a vector format that describes images as shapes, paths, text, and filter effects. The resulting files are compact and provide high-quality graphics on the web, in print, and even on resource-constrained, handheld devices. Users can magnify their view of an SVG image on‑screen without sacrificing sharpness, detail, or clarity. In addition, SVG provides superior support for text and colors, which ensures that users will see images as they appear on your Illustrator artboard.
The SVG format is entirely XML-based and offers many advantages to developers and users alike. With SVG, you can use XML and JavaScript to create web graphics that respond to user actions with sophisticated effects such as highlighting, tool tips, audio, and animation.
You can save artwork in SVG format using the Save, Save As, Save A Copy, or Save For Web & Devices command. To access the complete set of SVG export options, use the Save, Save As, or Save A Copy command. The Save For Web & Devices command provides a subset of SVG export options which are applicable to web-oriented work.
For a video on creating mobile content in Illustrator, see www.adobe.com/go/vid0207.
How you set up your artwork in Illustrator will affect the resulting SVG file. Keep in mind the following guidelines:
Use layers to add structure to an SVG file. When you save artwork in SVG format, each layer is converted to a group (<g>) element. (For example, a layer named Button1 becomes <g id="Button1_ver3.0"> in the SVG file.) Nested layers become SVG nested groups, and hidden layers are preserved with the SVG styling property “display:none”.
If you want objects on different layers to appear transparent, adjust the opacity of each object instead of each layer. If you alter opacity at the layer level, the resulting SVG file will not display transparency as it appears in Illustrator.
Raster data is not scalable in the SVG Viewer and cannot be edited like other SVG elements. If possible, avoid creating artwork that will be rasterized in the SVG file. Gradient meshes and objects that use the Rasterize, Artistic, Blur, Brush Strokes, Distort, Pixelate, Sharpen, Sketch, Stylize, Texture, and Video effects are rasterized when saved in SVG format. Similarly, graphic styles that include these effects also produce rasterization. Use SVG effects to add graphic effects without causing rasterization.
Use symbols and simplify the paths in your artwork to improve SVG performance. Also avoid using brushes that produce a lot of path data, such as the Charcoal, Fire Ash, and Scroll Pen, if performance is a high priority.
Use slices, image maps, and scripts to add web links to an SVG file.
A scripting language, such as JavaScript, opens unlimited functionality to an SVG file. Pointer and keyboard movements can invoke scripting functions such as rollover effects. Scripts can also use the document object model (DOM) to access and modify the SVG file—inserting or deleting SVG elements, for example.