Overview

If we have a data file located at _data/people.csv:

name,twitter
George,gphillips_nz
Mike,mikeneumegen
Ross,rphillips_nz

We can output the data in a list by looping of site.data.people:

...
<ul>
{% for person in site.data.people %}
  <li>
    <a href="https://twitter.com/{{ person.twitter }}">
      {{ person.name }}
    </a>
  </li>
{% endfor %}
</ul>
...