You can organise any reusable .liquid files into subdirectories under the /include folder, and then reference it from other liquid templates within the theme.

Example include file

<!-- /includes/footer/links.liquid -->
<p>Get in touch with us <a href="mailto:{{ page.support.email }}">by email</a></p>

Example use of the include

<!--- status-page.liquid -->
<footer>
  <!-- Include the footer links. -->
  {% include 'footer/links' %}
</footer>

When including the snippet, all the variables form the parent template are available, but you can also pass include-specific local variables if you wish. For more details on the include tag please take a look at the original Shopify documentation.