Can not find the tag library descriptor for “http://java.sun.com/jsp/jstl/core”

Use taglib definition in your JSP or better include it in every page by the first line.

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

There's also fix jstl-1.2 dependency in your project. Also use servlet specification at least 2.4 in your web.xml.

The maven dependencies are (maven is a open source development tool)

<dependency>
  <groupId>jstl</groupId>
  <artifactId>jstl</artifactId>
  <version>1.2</version>
  <scope>compile</scope>
</dependency>
<dependency>
  <groupId>taglibs</groupId>
  <artifactId>standard</artifactId>
  <version>1.1.2</version>
  <scope>compile</scope>
</dependency>

In the web.xml start writing

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

EDIT:

I'd like to add a note that @informatik01 has mentioned in the comment about newer version of JSTL libraries available from Maven repository: JSTL version 1.2.1 API and JSTL 1.2.1 .

I had the same problem even after I added jar files for jstl and standard. For me, it resolved after I added a Targeted runtime for my project.

Go to Project Properties > Targeted Runtimes and select the server you are using (Tomcat 7.0 for me).

create a libs folder in the inside WEB-INF directory and add jstl, standard jars as below.