Question: What is Xbox Live Silver?
Xbox Live Free (Silver) is a free version of the Xbox Live service. The main difference between the Gold and Free levels of service is that you can't play online multiplayer games with Xbox Live Free. You can still download content from the Xbox Live Marketplace, download games in the Xbox Live Arcade, and keep a friends list so you can chat and share your gamer profile and achievements.
Xbox Live Free has a couple of other disadvantages introduced more recently after the Xbox 360 first launched in 2005. With Free, you can't use Netflix on your Xbox 360, you can't watch ESPN, and some demos and other content may be delayed for free users while Gold members get it first.