ansible tags only when tag defined code example

Example 1: ansible tags

ansible-playbook example.yml --tags "configuration,packages"

Example 2: ansible tags

tasks:
- yum:
    name:
    - httpd
    - memcached
    state: present
  tags:
  - packages

- template:
    src: templates/src.j2
    dest: /etc/foo.conf
  tags:
  - configuration