Storing List in System.Web.HttpRuntime.Cache, is it serialized?

Trying to find out if the System.Web.HttpRuntime.Cache or any other possible caching is serialized?

Basically i need to store list in Cache, and it has to be Read/Write by many users.

So, I can out a list in cache, i can get it back out. What happens when many people try to access the list? Do i have to lock the list? when changing it, I'm开发者_JAVA技巧 guessing I'll have to re-add the list.

Or any other suggestions? Besides using the DB or writing to a file.

Came up with a possible solution. Since my list was going to contain a GUID anyway, I could just use the Cache it self as a list, using the GUID as the Key.

But I am still curious if objects or cache still need to be locked when access them, and re-adding them back to the Cache?