We're glad you asked! SVG stands for "Scalable Vector Graphic." In reality, it's just a another type of image file, like PNG, JPG, TIFF, etc. Any professional or amateur graphic designer with access to photoshop or Sketch should know what an SVG is and how to create one.
Our app exclusively uses SVG graphics to generate your custom 3D model. If you have another type of image file and want to make an SVG, here is a free online converter that we use all the time: https://image.online-convert.com/convert-to-svg.