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 most commonly used tags in the fmt tag library is the <fmt:parseDate> tag, which is used for parsing dates and converting them to a specific format.

The <fmt:parseDate> tag takes a string representation of a date and parses it into a java.util.Date object, which can then be formatted using other tags in the fmt tag library. The syntax of the tag is as follows:

<fmt:parseDate value="dateString" [pattern="dateFormatPattern"] [var="varName"] />

where dateString is the string representation of the date to be parsed, dateFormatPattern is the format pattern used to parse the date (if not specified, the default format pattern for the current locale is used), and varName is the name of the variable to store the parsed date.

For example, to parse the date "2023-02-16" using the default format pattern for the current locale, you would use the following tag:

<fmt:parseDate value="2023-02-16" var="parsedDate" />

This tag parses the date string "2023-02-16" into a java.util.Date object and stores it in the variable parsedDate.

You can also specify a custom date format pattern to parse the date. For example, to parse the date "02/16/2023" using the format pattern "MM/dd/yyyy", you would use the following tag:

<fmt:parseDate value="02/16/2023" pattern="MM/dd/yyyy" var="parsedDate" />

This tag parses the date string "02/16/2023" using the specified format pattern and stores the parsed date in the variable parsedDate.

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.