Inkscape is a free and open-source vector graphics editor; it can be used to create or edit vector graphics such as illustrations, diagrams, line arts, charts, logos and complex paintings. Inkscape’s primary vector graphics format is Scalable Vector Graphics (SVG), however many other formats can be imported and exported.
Inkscape can render primitive vector shapes and text. These objects may be filled with solid colors, patterns, radial or linear color gradients and their borders may be stroked, both with adjustable transparency. Embedding and optional tracing of raster graphics is also supported, enabling the editor to create vector graphics from photos and other raster sources. Created shapes can be further manipulated with transformations, such as moving, rotating, scaling and skewing.
It is considered lightweight free alternative to “Illustrator”. What I like most about vector images is that you can export image to any resolution wanted, suitable for various medias.
This is SVG image made in Inkscape by Rizky Djati Munggaran: