What is "salvage?" Or more aptly, what do you want out of it?

[BadgerBadger]

One of the things I really like about salvage is it gives me a sense of accomplishment when I beat a giant attack; "Wow, there's 4 million salvage on Murdoch! That was an epic fight; last time I repelled the AI assault it was only 2 million". This is especially true on Fallen Spire, since it gives me a sense of how much bigger each Exo wave was.