What Are Vector Graphics? SVG, AI and EPS Explained
Vector graphics are images built from mathematical paths, points, lines, and curves defined by equations, rather than from a fixed grid of pixels. Because they are described by math, vectors can scale to any size without losing a shred of quality: the same file works as a 16-pixel favicon or a building-sized banner. This guide explains how vectors differ from raster images and what the SVG, AI, and EPS formats actually do.
If you have ever wondered why a designer insists on the “vector files” for your logo, this is the answer. A logo lives at every size imaginable, and only a vector can survive that range cleanly.
Vector vs Raster: The Core Difference
There are two fundamental ways to store an image, and understanding the split is everything:
- Raster (bitmap) images are a grid of colored pixels. JPG, PNG, and GIF are raster. Photographs are inherently raster. When you enlarge a raster image past its native resolution, it blurs or shows blocky, jagged edges, because there are no extra pixels to fill the new space.
- Vector images store shapes as math. A circle is “a circle of radius r centered here,” not thousands of pixels. Scale it up and the software simply recalculates the curve, so edges stay perfectly crisp at any size.
The practical rule: use vectors for anything that needs to scale or stay crisp, logos, icons, illustrations, type. Use raster for photographs and complex, painterly images that vectors cannot realistically describe.
| Property | Vector | Raster |
|---|---|---|
| Built from | Math: paths and points | Grid of pixels |
| Scaling | Infinite, no quality loss | Loses quality when enlarged |
| Best for | Logos, icons, illustration, type | Photos, detailed imagery |
| File size | Small for simple art | Grows with resolution |
| Editable | Every shape stays editable | Pixels are baked in |
How Vectors Are Made
Vectors are drawn in vector software using paths controlled by anchor points and Bézier handles, the curves you pull to shape a line. The three main tools are:
- Adobe Illustrator, the industry standard, which produces native AI files.
- Affinity Designer, a one-time-purchase alternative with no subscription.
- Inkscape, free and open source, which works natively in SVG.
Because every shape remains an editable object rather than fixed pixels, you can recolor, resize, and restructure vector art endlessly without degrading it.
SVG, AI, and EPS: What Each Format Does
The three vector formats you will meet most often each have a distinct role:
SVG (Scalable Vector Graphics)
SVG is the web vector format. It is actually a text-based XML file, so it is small, it scales perfectly on any screen and pixel density, and it can be styled and animated with CSS and JavaScript. Use SVG for logos, icons, and illustrations on websites and apps. It is the modern default for anything vector on the web.
AI (Adobe Illustrator)
AI is Adobe Illustrator’s native working file. It preserves every layer, editable path, and effect, which makes it the master file you keep and edit from. AI files are not for sharing with the public or placing on a website; they are the editable source you export other formats from. Always keep the AI (or equivalent native) file safe, because it is the only fully editable original.
EPS (Encapsulated PostScript)
EPS is an older, highly compatible vector format. Its strength is universality: it opens in almost any professional design or print software, which is why print shops and sign makers still request it. It is less relevant for the web but remains a reliable handoff format for print vendors and partners who use different software than you do.
| Format | Best use | Editable? |
|---|---|---|
| SVG | Web and app graphics | Yes, and code-friendly |
| AI | Master working file | Yes, full editing |
| EPS | Print and cross-software handoff | Yes, broadly compatible |
| Sharing and print-ready output | Partially |
PDF deserves a mention too: it can hold vector data and is excellent for sharing print-ready files that look identical everywhere. For a fuller breakdown of which logo files to keep and deliver, see our guide to logo file formats.
When to Use Vector vs Raster
The decision is almost always clear once you know what the image is:
- Logos and icons: always vector. They must scale from favicon to billboard.
- Illustrations and infographics: usually vector, especially if they need to scale or be edited later.
- Type and lettering for branding: vector, so it stays sharp at any size.
- Photographs: always raster. No vector format can realistically describe a photo.
- Web graphics: SVG for vectors, optimized PNG or WebP for photographic content.
One subtlety worth knowing: fonts are themselves vector data, which is why type stays crisp at any size, and why font files have their own formats. If you work with type often, our explainer on font file formats covers how those vector outlines are packaged into TTF, OTF, and web font files.
Converting Between Vector and Raster
Exporting a vector to raster (to PNG or JPG) is easy and lossless at the size you choose; you simply “rasterize” it. Going the other way, turning a raster image into a true vector, is hard. Auto-tracing tools can approximate it for simple, high-contrast shapes, but a detailed photo cannot be meaningfully vectorized. This is exactly why you should always keep the original vector master file: once a logo exists only as a low-resolution PNG, recreating clean vector art means redrawing it by hand.
Frequently Asked Questions
What is the difference between vector and raster graphics?
Vector graphics are built from mathematical paths and scale to any size without losing quality, making them ideal for logos and icons. Raster graphics are grids of pixels, like JPGs and PNGs, that blur or pixelate when enlarged but are necessary for photographs. Use vector for scalable art and raster for photos.
What is the best vector format for the web?
SVG is the best vector format for the web. It is a small, text-based file that scales perfectly on any screen and pixel density and can be styled or animated with CSS and JavaScript. Use SVG for logos, icons, and illustrations on websites and apps.
What is the difference between AI, EPS, and SVG?
AI is Adobe Illustrator’s native master file with full editability, kept as your source. SVG is the web format, small and code-friendly. EPS is an older, highly compatible format that print shops and sign makers still request because it opens in almost any professional software.
Can you convert a raster image to a vector?
Only with limitations. Auto-tracing tools can approximate simple, high-contrast shapes into vectors, but detailed photographs cannot be meaningfully vectorized. This is why keeping the original vector master file matters: recreating clean vector art from a low-resolution raster usually means redrawing it by hand.
