How can I use tag slugs in URLs?
The key to this is to use the |kebab filter and the relatedTo params.

Listing:

{% for tag in relatedTags %}
    &lt;li&gt;&lt;a href="/news/tags/{{ tag.title|kebab }}"&gt;{{ tag.title }}&lt;/a&gt;&lt;/li&gt;
{% endfor %}


Fetch related articles

{% set tag = craft.tags.search(craft.request.getSegment(4)) %}

{% for entry in craft.entries.relatedTo({ targetElement: tag[0], field: tagField }) %}


The tag[0] is necessary, as {{ craft.tags.search() }} will return an array (even if there's only one tag returned).

This finds entries that are specifically related to Two Words (a tag object, pulled from the URL), and searches in the tagField specified.

The alternative to the above is to use {{ tag.id }} and {{ craft.tags.id() }}, but that isn't URL/SEO friendly.