How can I get an entry's child category, and not the parent category? I have a category page that lists all of the entries related to that category. And then I want to display the selected child category for the entry... in brief like so:

Entry Title 1
Entry 1's Child-Category

Entry Title 2
Entry 2's Child-Category

Entry Title 3
Entry 3's Child-Category

My category field handle is chooseLocation

Here is what I have in my template:
(snippet taken from here)

{% for entry in entries %}
    {% if entry.chooseLocation | length %}
    {% for category in entry.chooseLocation %}
         &lt;a href="/location/{{ category.slug }}"&gt;{{ category }}&lt;/a&gt;
            {% if not loop.last %}, {% endif %}
        {% endfor %}
    {% endif %}
{% endfor %}


The problem is, this get's the parent category (which is the category page we're on) but not the child category. I need to show just the child category and not the parent.  

I've looked through the docs but I can't find anything on how to do this.
Your Categories field (entry.chooseLocation) is an Element Criteria Model. It's exactly the same as if you'd done something like this...

craft.categories.group('myGroup')


The Element Criteria Model (ECM) is an important concept in Craft, because it's the driver for most content handling. Once you've got a bearing on what the ECM is, you can use it fairly consistently.

For example, just like craft.entries, you can apply .find, .first, and other methods to retrieve a specific subset of elements. And depending on the element type, you can chain other filtering methods in between...

craft.categories.group('myGroup').limit(3).find()


Returning to your question, entry.chooseLocation will be an ECM for Categories. So it's just a matter of filtering it appropriately.

{% for category in entry.chooseLocation.level(2).find() %}


Here is the full list of filtering options you can use on a Categories ECM.