What exactly does "@safe" mean?

[monarch_dodra]

The way I understood it, @safe defines a list of things that are 
or aren't legal inside the implementation of a function. It also 
changes the scheme of bounds checking, in release code.

What bothers me though, is that from an interface point of view, 
it doesn't really mean anything (or at least, I haven't really 
understood anything). AFAIK: if I call something "@safe", chances 
of a core dump are relatively "lower", but they can still happen:
* A function that accepts a pointer as an argument can be marked 
safe, so all bets are off there, no, since the pointer can be 
dereferenced?
* Member functions for structs that have pointers, too, can be 
marked safe...

Or does it only mean "if you give me valid pointers, I can't core 
dump*"?
(*ignoring current flaws, such as escaping slices from static 
arrays)

The main reason about this question is that now I'm confused 
about @trusted: what are the conditions a developer needs to take 
into account before marking a function "@trusted" ?

Ditto for member functions, when they operate on pointer members. 
Can those be @safe?

Yeah, overall, I'm confused as to what "@safe" means from an 
interface point of view :(