What does this graphic stock called?

Hi,
I'm looking for these kind of colorful waves which Microsoft® massively use for their Windows™ (mostly Vista and 7) [as banners, splashes, wizards side-pics, Media center footer and etc.], for my applications themes and product branding.

The problem is I don't know what are they called! =))) I tried "windows*blue*waves" and other combinations concentrated on *.png and transparent *.gif or even *.avi to beside being goodlooking, performs a sort of loading and fluent ui but not a desired results. Does anyone know where can I get one not even in free?

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Are you looking for Fluent?

https://developer.microsoft.com/en-us/fluentui#/styles