Vector graphics *describe* shapes rather than store pixel data. To display a vector image, the rendering engine has to interpret the vector shape data and convert it to a raster (pixelated) image at whatever pixel resolution is desired. So zooming a vector graphic results in it being re-rasterized at higher resolution, and since the original data describes the shapes independently of any fixed resolution, you can do so with no quality loss

“Raster” graphics represent an image as a grid of rectangular pixels of varying color. If the pixels are small then the image looks smooth, but look closer and eventually you can see those rectangular chunks. Sharp borders of color at certain angles will look jagged.

Vector graphics represent an image by mathematical formula which chart lines and curves. They can be calculated to any precision you desire so your display device (which is using pixels itself) can always produce output at the limit of its possible resolution, meaning it always looks as smooth as possible no matter the zoom.

A **vector** is based on **math**; the computer will always be calculating what to show at a specific zoom level, as the “data” is not based on pixels. That step of pixilation only comes later. You zoom in, it recalculates and updates the display.

A **raster** image is entirely **pixel-data**. It’s detail is limited to the level the pixel data is stored at, so when you zoom in, there’s nothing else to do but fill gaps with data from the neighboring locations.

Have you ever used a graphing calculator?

If you create a graph of an equation on a graphing calculator, the calculator will be able to draw it no matter what your zoom level is. That’s because the graph itself is just pure math; the calculator is computing what it looks like on-the-fly based on the math.

Some people make a hobby out of trying to draw shapes and pictures in graphing calculators. If you find the right math equations and plug them into a graphing calculator, the calculator will draw your drawing for you.

Vector graphics work like that. No… not *like* that. That is *literally exactly* how vector graphics work. Vector graphics files are just lists of math equations. When it’s time to draw the graphic to the screen, the computer solves the equations, exactly how a graphing calculator would, and shows you the result.

You can infinitely zoom in on it because, under the hood, it’s just pure math. Math doesn’t end. All zooming in farther does is change the computation the computer has to do to show you the image, which it will happily do on-the-fly.

You know those little bright dots you see in the sky at night time? All of them are very far away. Some of them are more far away than others, but all of them are far enough away that they all look the same size in the sky at night regardless of the fact that each star is a different size and different distance away. Stars are like vector graphics.

Raster graphics are more like the moon. Some days the moon is big and bright and close. Some days the moon appears very far away and small. Some days you can only see half of the moon. And some days you don’t see the moon at all. Despite the fact that the moon isn’t actually changing size or shape or moving in any dramatic way like it appears to be.

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