One of the first things that I learned when writing code was to copyright it. As far as I know, the things to do are:
Create a license file that describes the copyright and lists the software files.
Add the copyright to each file containing code. Ex:
# (C) Copyright <years> <name>. <license>.
[Optional] Register the software into official organizations of intellectual property.
the stages 1) and 2) I've always seen it in heavy client software, but I ignore why big corporations like Facebook, Google, Microsoft, etc... never do it in their web code (speaking about step 2). And they also don't even use the HTML meta tags:
<meta name="author" content=""> <meta name="copyright" content="">
Is there any legal reason behind this? Is their code already declared on step 3 so they don't bother doing step 2?