Web designers use a variety of different tools depending on what part of the production process they are involved in. These tools are updated over time by newer standards and software but the principles behind them remain the same. Web designers use both vector and raster graphics editors to create web-formatted imagery or design prototypes. Technologies used to create websites include W3C standards like HTML and CSS, which can be hand-coded or generated by WYSIWYG editing software. Other tools web designers might use include mark up validators[7] and other testing tools for usability and accessibility to ensure their websites meet web accessibility guidelines.[8]