Listing categories alphabetically & total post count How do I list all categories in use alphabetically? And how to get the total post count from each category? 

Cheers﻿
The relatedTo param will do the trick:

{% set entries = craft.entries.limit(null) %}
{% for category in craft.categories.relatedTo(entries).order('title asc') %}
    {% set entryCount = entries.relatedTo(category).total() %}
    {{ category }} ({{ entryCount }})
{% endfor %}