1. A computer implemented method for processing permission tags embedded by a server to enable a client to identify executable or non-executable regions in content received by the client, comprising: sending a request from the client to the server for the content, wherein the client sends the request to the server through a browser running at the client, wherein the browser is configured to include: an opt-in setting that, when activated, causes the browser to run all executable content unless expressly forbidden by a permission tag, and an opt-out setting that, when activated, causes the browser to run no executable content except that which is expressly permitted by a permission tag; receiving the content embedded with one or more permission tags from the server, wherein each of the permission tags comprises a permission attribute that indicates whether any script following the tag is to be executed; processing the content and the one or more permission tags; and granting permission to the browser to execute the content based on the one or more permission tags in the content.