SVG Sprites – Complete Lesson

1. What is an SVG Sprite?

An SVG sprite is a single SVG file that contains many small graphics (icons, logos, UI glyphs), each wrapped in its own <symbol> element.
You load the sprite once, then reference any icon inside it with <svg><use href="#my-id"></use></svg>.
This reduces network requests and keeps every icon razor-sharp on all screens.

2. Why Use SVG Instead of Raster Sprites?

Key advantages

• Resolution-independent – vectors stay crisp at any zoom or DPI.
• Easy theming and animation – change fill, stroke, add CSS transitions, or animate with SMIL / JS.
• Accessibility – each symbol can include <title> or <desc> for screen-reader support.
• Smaller file size – a gzipped SVG sprite for flat icons is usually lighter than several PNGs.
• One request, many icons – the entire set downloads once and can be cached.

3. Why Use Raster Sprites Instead of SVG?

When Raster (PNG / JPG) Sprites Still Beat SVG

• Photographic or Textured Assets
  • SVG is vector-only; it can’t reproduce photo realism, gradients with noise, film-grain textures, or pixel-art nuances.
  • If your sprite sheet contains thumbnails, emoji, or bitmap UI skins, raster is the only option.
• Pixel-Perfect Consistency
  • Some interfaces depend on exact pixel grids (e.g., 8-bit game art, bitmap fonts).
  • Scaling vectors can introduce anti-aliasing or sub-pixel blurring, whereas a PNG sprite delivers the same pixels everywhere.
• Legacy Browser or Email Support
  Inline/external SVG <use> is unsupported or buggy in:
  • Outlook desktop clients
  • Older Android WebViews
  • Very old IE/Edge versions without polyfills
    PNG sprites work back to IE 6 and in virtually every email client.
• Lower CPU Overhead for Many Tiny Icons
  • Parsing hundreds of inline SVG paths can trigger more DOM and paint work than drawing a single bitmap.
  • For ultra-lightweight embedded widgets (ads, dashboards) a single 10 kB PNG sprite can actually be faster to decode and render.
• HTTP/1 Constraints
  
  • On legacy sites that can’t use HTTP/2 or HTTP/3, each additional request is expensive.
  • A single raster sprite removes dozens of HTTP round-trips without requiring the <svg><symbol> pattern or JS polyfills.
• No Build Pipeline Needed
  
  • Designers can export one combined PNG from Photoshop/Figma and hand it off.
  • SVG sprites often benefit from SVGO optimization, viewBox alignment, and IDE tooling—overkill for quick prototypes.
• Security-Sensitive Environments
  • Inline SVG can carry scripts, external references, or event handlers.
    Some CMS or ad networks strip <svg> completely; raster sprites remain whitelisted.

Rule of Thumb

• SVG sprite: Flat, single-color or outline icons
• Raster sprite: Detailed photos, emoji, pixel-art UI

Modern projects often mix both: SVG for clean line icons, PNG/JPG sprites for complex bitmaps.

Example: