Example for comment in https://devops.stackexchange.com/questions/13618

ex.yml

# This is an old ini style
- name: Set some vars
  set_fact: var1=toto var2=titi
  
# Yaml style is easier to read...
- name: Set some vars
  set_fact:
    var1: toto
    var2: titi
    
# ..and is more flexible with real use cases (Note mandatory quotes arrount the jinja value since it starts with a double moustache)
- name: Set complex vars ini
  set_fact: a_list=["element1","element2"] a_dict={"key1":"value1"} a_word=toto a_string="I'm a phrase" jinja_string="{{ some_var }}"

- name: Set complex vars yaml
  set_fact:
    a_list:
      - element1
      - element2
    a_dict:
      key1: value1
    a_word: toto
    a_string: I'm a phrase
    jinja_string: "{{ some_var }}"  # mandatory quotes in ansible because it starts with double moustache
    other_string: "The value of var is {{ some_var }}"  # Not mandatory here but I suggest you keep them as a good practice