The Shockwave Player is a web plugin that allows you to play multimedia files. The player was also used for interactive web content like games, business presentations and anything from entertainment to advertisements. The player was needed to display content created with Adobe Director. However, Shockwave Player isn't used so much nowadays with Adobe Flash Player and Adobe Air on the market.
To find more about it, access the official support page at Adobe: https://helpx.adobe.com/shockwave/kb/shockwave-player-faq.html