Based on the JSTL functions, they are categorized into five types:-
Core Tags – Core tags provide support for iteration, conditional logic, catch exception, url, forward or redirect response etc.
Formatting and Localization Tags – These tags are provided for formatting of Numbers and Dates support through locales and resource bundles.
SQL Tags – JSTL SQL Tags provide support for interaction with relational databases such as Oracle, MySql etc.
XML Tags – XML tags are used to work with XML documents such as parsing XML, transforming XML data and XPath expressions evaluation.
JSTL Functions Tags – JSTL tags provide a number of functions that we can use to perform common operation, most of them are for String manipulation such as String Concatenation, Split String etc.