Determines whether the query is for an existing single post.

Determines whether the query is for an existing single post of any post type (post, attachment, page, custom post types).

Determines whether the query is for a specific time.

Determines whether the query is for a trackback endpoint call.

Determines whether the query is for an existing year archive.

Given an ISO 8601 timezone, returns its UTC offset in seconds.

Given an ISO 8601 (Ymd\TH:i:sO) date, returns a MySQL DateTime (Y-m-d H:i:s) format used by post_date[_gmt].

Load default translated strings based on locale.

Loads a plugin’s translated strings.

Require the template file with WordPress environment.