Where is cortana in Windows phone 10?

[Iftekhar Apu]

Where is Cortana? i tried by region and language changed to usa and reboot it. but no cortana in windows 10 mobile. I'm using lumia 640xl.

 

[abhishek singh21]

Where is Cortana? i tried by region and language changed to usa and reboot it. but no cortana in windows 10 mobile. I'm using lumia 640xl.

is it available in the app list ? Are you an insider on fast ring?