Steam was first announced by Valve in March of 2002, and would go into beta soon after. The service however, wouldn't commence operations until September 15, 2003.
On August 15, 2014, Steam's logo was given a refresh, that was made a new icon. Additionally, a new font was incorporated alongside the logo on the main client. Though it wasn't until sometime in 2016, when the new logo and wordmark was finally incorporated into the website. As of September 2018, the current logo is now also used as a favicon, replacing the previous one that had been used since the service's launch.