The California law says users must explicitly agree to receive e-mail from each advertiser.

However, a signed applet can have full access to the machine it is running on if the user agrees.

"But we really feel like all the effort is worth it and we re sure our users will agree."

In exchange for the computers, users agree to put up with a constant stream of advertising and provide personal information to be used by advertisers.

A free version of the service remains, although users must agree to accept ads on their Weblogs.

The user agrees and says, yes, this is what I want to do.

With this form each user agrees to abide by the rules of the Verify information system.

All Facebook's 800 million users, whether they realise it or not, agree to let the company use of their personal information.

In exchange for these free services, users agree to let a piece of software track their activity as they surf the Web.

All users of the Website hereby specifically agree to such monitoring.