Photoshop edition puzzle

[raymo]

Can anyone tell me how the editions of PS relate to each other. I have the old PS 7. How did the numbering system work? Why are some labelled
CS something or other, and how do I know where my 7 fits in the scheme of things. Also, is there any way of updating my 7?
raymo

[pluto]

They were numbered PS 1 through 7.
Then instead of 8 they started calling is CS as part of the Creative Suite branding.
There was CS versions 1 through 6.
Then they changed to a subscription model and called it CC, as in Creative Cloud.
There has been one update since moving to CC and it's called, imaginatively, Photoshop CC 2014.

EDIT: I missed the last part of your question
I don't think there's an upgrade path from PS7.
If you want the current version you'll have to pay a monthly fee. I think they still have the deal I'm on where I pay $10 per month for PS plus Lightroom.

[raymo]

Thank you so much for your comprehensive reply Hugh, much
appreciated.
raymo