Ansible play recap doubt

In the play recap(summary) does the OK tab means the “total number of tasks which were not changed + which were changed”. In other words, the tasks which didn’t fail?
I was under the impression it was the tasks which didn’t change. But the following task output says otherwise. I could not find any documentation on this.

PLAY [all] *********************************************************************

TASK [setup] *******************************************************************
ok: [10.128.12.5]
ok: [10.128.12.6]

TASK [task1 ] ******************************************
changed: [10.128.12.5]
changed: [10.128.12.6]

TASK [task2] ******************************************
changed: [10.128.12.5]
changed: [10.128.12.6]

PLAY RECAP *********************************************************************
10.128.12.5                 : ok=3    changed=2    unreachable=0    failed=0   
10.128.12.6                 : ok=3    changed=2    unreachable=0    failed=0