Determines whether WordPress is already installed.

Is the server running earlier than 1.5.0 version of lighttpd?

Determine whether a network is the main network of the Multisite installation.

Determine whether a site is the main site of the current network.

Determines whether the publish date of the current post in the loop is different from the publish date of the previous post in the loop.

Checks compatibility with the current PHP version.

Check value to find if it was serialized.

Check whether serialized data is of string type.

Determines whether site meta is enabled.

Checks compatibility with the current WordPress version.