Virtual graffiti consists of virtual or digital media applied to public locations, landmarks or surfaces. Virtual graffiti applications utilize augmented reality and ubiquitous computing to anchor virtual graffiti to physical landmarks or objects in the real world. The virtual content can then be viewed through digital devices. Virtual graffiti is aimed at delivering messaging and social multimedia content to mobile applications and devices based on the identity, location, and community of the user. Mediums This overall effort focuses on creating new mobile experiences based on merging virtual reality, telepresence, and global positioning systems. These experiences evolve over time based on the needs and capabilities of the users. Location-based messaging This medium regards a mobile user receiving or sending a message based on their location. The content quality is directly related to the accuracy of the user's location. These include experiences such as: Searching where the nearest restaurant is and receiving a set of messages and coupons from nearby restaurant proprietors. Receiving a message on their mobile device that there is traffic ahead with a suggested alternative route. Coworkers receive a notification that an upcoming meeting has been moved to a new location. Location anchored virtual reality This involves anchoring a virtual reality experience at a physical location. Thus the experiences in the virtual world can only be had at a specific real location. Several use cases that are included here are: A virtual command post can be set up at the scene of an incident. This command post involves the sharing of information in the virtual world but can only be accessed by those at the scene of the incident. A set of blogs and media files are left at famous outdoor sculptures. Groups of friends can contribute, copy, and share files only while they are viewing the sculpture. Background The phrase "virtual graffiti" has existed for a long time and has been applied to various applications over the years. Originally, it referred to posting messages on electronic bulletin board systems. From there, it has developed in academia into contextual messaging applications. Contextual messaging Contextual messaging refers to leaving some type of context-specific annotation, e.g., a virtual Post-it Note on a computer monitor, a time-sensitive message attached to a wall, or location-based graffiti on a physical object. Researchers at the University of Salford experimented with a Cave system in which a user could mark up a scene using 6-degree freedom