[philh]

They're faster to type, and I suspect I find them more pleasant to read (this is hard to test). AIUI, IIRC and similar are good disclaimers to make, but they're basically boilerplate, and don't need to take up lots of space.

Similarly, compare "(c) 2015 philh" to "this post is copyrighted by philh, as of 2015".

[sib]

<trivia> Interestingly enough, (c) 2015 philh does not meet the requirement. You need either the word, copyright, or the actual copyright symbol. </trivia>

[heinrich5991]

IIRC you don't need any of this, you will still hold copyright to what you have produced. This is just a friendly reminder to your readership.

[Natsu]

Correct. The Berne Convention did away with 'formalities' like having to register your copyrights in order to hold them. You still need to have a registered copyright to sue for statutory damages in the USA, though.

[colinbartlett]

IANAL but I believe you are correct although you get some extra legal protections by including the notice (which only need include the word or symbol and the name and year). Namely, an infringer cannot claim they did so accidentally... or something like that. FWIW.

[InclinedPlane]

No, you do not. Any work you do is automatically under copyright as long as that is a reasonable expectation (given a site's TOU, etc.)