Web page design requires conceptualizing, planning, modeling, and executing electronic media content and its delivery via the Internet using technologies (such as markup languages) suitable for rendering and presentation by web browsers or other web-based graphical user interfaces (GUIs). The intent of web design is to create a web site (a collection of electronic files residing on one or more web servers) that presents content (including interactive features or interfaces) to the end user in the form of web pages upon request. Such elements as text, forms, and bit-mapped images (GIFs, JPEGs, PNGs) can be placed on the page using HTML, XHTML, or XML tags. Displaying more complex media (vector graphics, animations, videos, sounds) usually requires browsers to incorporate optional plug-ins, such as Flash, QuickTime, and Java run-time environment. Other plug-ins are embedded in web pages, using HTML or XHTML tags. Improvements in the various browsers' compliance with W3C standards prompted a widespread acceptance of XHTML and XML in conjunction with Cascading Style Sheets (CSS) to position and manipulate web page elements. The latest standards and proposals aim at leading to the various browsers' ability to deliver a wide variety of media and accessibility options to the client possibly without employing plug-ins.