In an open letter to advertisers, the IAB (Interactive Advertising Bureau) and other co-signing firms such as major publishers and advertising agencies have drafted a letter urging advertisers to begin to support and leverage the HTML5 standards for building ad creative which runs across all platforms stating “To guarantee the ads you pay for actually appear and look great on all screens, you should insist to your ad agencies that your advertising creative be developed in a mobile-compatible format. And the one open, industry-standard, universal format for building mobile-ready creative is HTML5,” which goes on to suggest such things as the requirement for new tools and approaches as well as the some of the benefits of performing the requested actions. In addition to the IAB, the co-signers include AOL, BlogHer, Conde Nast, Forbes, Google, IDG, Millennial Media, Slate, New York Post, The New York Times, Time Inc., Undertone, Conversant, The Wall Street Journal, The Weather Company, and Xaxis. Read the full contents of the letter here.