Why do we need exclude in pom : <p>Pom.xml have this elements and I am curious why do we need exclude <code>commons-logging</code> from <code>spring-core</code>? And how do it works?</p>

<pre><code>&lt;dependency&gt;
        &lt;groupId&gt;org.springframework&lt;/groupId&gt;
        &lt;artifactId&gt;spring-core&lt;/artifactId&gt;
        &lt;version&gt;3.0.5.RELEASE&lt;/version&gt;
        &lt;type&gt;jar&lt;/type&gt;
        &lt;scope&gt;compile&lt;/scope&gt;
        &lt;exclusions&gt;
            &lt;exclusion&gt;
                &lt;artifactId&gt;commons-logging&lt;/artifactId&gt;
                &lt;groupId&gt;commons-logging&lt;/groupId&gt;
            &lt;/exclusion&gt;
        &lt;/exclusions&gt;
    &lt;/dependency&gt;
&lt;!-- next is log4j dependencie --&gt;
</code></pre>
