Not every image you make in Illustrator is visible once you save it. Therefore, it is very essential to know how to work with paths and appearances in Adobe Illustrator. Once you create a path in Illustrator, it will not appear as the final image unless strokes are applied or color is filled in it. Hence, one needs to have the basic knowledge of strokes in Illustrator and Illustrator fills, be it color or gradient or any other, when creating a vector image in this software.