The JSTL (JavaServer Pages Standard Tag Library) fmt tag library provides a set of tags for formatting and internationalizing data in JSP (JavaServer Pages) pages. One of the tags in the fmt tag library is the <fmt:timeZone> tag, which is used to display the time zone of a date or time.

The <fmt:timeZone> tag is used to display the time zone of a date or time. The time zone is displayed as an offset from Coordinated Universal Time (UTC). The tag can be used with the <fmt:formatDate> tag to display the time zone of a formatted date or time. The syntax of the tag is as follows:

<fmt:timeZone [value="timeZoneValue"] />

where timeZoneValue is the value of the time zone to use (optional).

For example, to display the time zone of the current date and time, you would use the following tags:

<fmt:setTimeZone value="America/Los_Angeles" />
<fmt:formatDate value="${now}" pattern="yyyy-MM-dd HH:mm:ss z" />
<fmt:timeZone />

This code sets the time zone to use for formatting dates and times to Pacific Standard Time (PST), formats the current date and time using the pattern yyyy-MM-dd HH:mm:ss z, and then displays the time zone as an offset from UTC.

If the value attribute is not specified, the time zone of the fmt:setTimeZone tag that is closest in scope to the <fmt:timeZone> tag is used. If no fmt:setTimeZone tag is found, the time zone of the server is used.

Note that the fmt tag library must be imported at the beginning of the JSP page using the following tag:

<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>

This imports the fmt tag library and assigns it a prefix of fmt.