Basically, when you start a company, you choose to start it (to incorporate it) in a particular state. Each state has its own laws about corporations, what they are and aren't allowed to do, etc.
Some states have laws that are really company-friendly, and other states have laws that are really shareholder-friendly. Delaware's laws are, in general, quite company-friendly -- so when you're starting your company, it makes a lot of sense to do so there (because your company will get the most legal protection).
In addition, "basically everyone else does it". Which isn't good motivation for jumping off a bridge, but it is a good motivation here, and here's why: case law.
Lots of companies (and thus lots of Delaware companies) have done crazy things and have had lawsuits over them. So it's better-understood how to interpret portions of Delaware corporate law, because they've been tested before in court. Whereas in some other random state, that's less likely to be the case. As a consequence, I think basically every corporate lawyer in the US is familiar with both their own state's corporate law, as well as Delaware's.
And finally, a disclaimer: I'm not intimately familiar with the corporate law of even just one state, let alone all 50, so take this with a grain of salt -- but this is a sketch of the motivations for incorporating in Delaware that I've heard.
Some states have laws that are really company-friendly, and other states have laws that are really shareholder-friendly. Delaware's laws are, in general, quite company-friendly -- so when you're starting your company, it makes a lot of sense to do so there (because your company will get the most legal protection).
In addition, "basically everyone else does it". Which isn't good motivation for jumping off a bridge, but it is a good motivation here, and here's why: case law.
Lots of companies (and thus lots of Delaware companies) have done crazy things and have had lawsuits over them. So it's better-understood how to interpret portions of Delaware corporate law, because they've been tested before in court. Whereas in some other random state, that's less likely to be the case. As a consequence, I think basically every corporate lawyer in the US is familiar with both their own state's corporate law, as well as Delaware's.
And finally, a disclaimer: I'm not intimately familiar with the corporate law of even just one state, let alone all 50, so take this with a grain of salt -- but this is a sketch of the motivations for incorporating in Delaware that I've heard.