Not web dev question - I'm curious, what is the advantage of using a font rather than images?

Font files are vector "images" which means your icons will scale gracefully to any size. This is probably the main advantage.

Depending on the complexity I imagine fonts would also be smaller than corresponding bitmaps although I never actually checked.

SVG are vector graphics that can be rendered in all modern browsers:

http://caniuse.com/#feat=svg-img

You do miss out on the recoloring and any other font styling options though.

Actually you can style SVG with CSS

    #yourSVG {
        fill: red;
        stroke: blue;
    }

I don't think you can re-style a SVG with CSS if you embed it with IMG. CSS styling has to be inline with the SVG, so you can embed it directly, or you can change CSS with JS.

mind = blown

The problem is that, until <svg use> is standardized and supported, the only way to style svg elements is if you include them in your markup (or use something like Iconic's SVG Injector).

There's a tradeoff between inlining (or rather, including them server-side) and calling them as <img>, background-image, or fonts. The size, http requests, caching , and styling all play a role.

They can also be recolored more easily, making themes easier to maintain.

But they can only be one color. I don't think gradients and stuff work on them.

There are ways to use multiple colors:

http://www.pixelambacht.nl/2014/multicolor-icons/

You can change the color and size without having to change or edit an image. Plus things like pixelation dont happen with fonts but you could use canvas in a similar way. I've seen some cool logos done with canvas.

Less http petitions and bandwidth. Also, they are vector-based so are great for all resolutions and sizes.

Why is this being downvoted? Did I say anything false?

If you had a closer look on the page and the FAQ section you would have noticed that there is a manifest file that you can load into IcoMoon and select your desired fonts to use, minimising the size of the fontset. PS Font awesome is much much more big in size.

Unless you're missing a 0, does a file size like that really matter?

On mobile, yes. Even on good networks, you don't always have a strong signal. Download size is always a factor on mobile. 35kb isn't a big deal if it were needed but if 90% of the download is wasted then you probably don't want that.