I'd need a GSoC2015 tag (I've requested the students to tag it that way so it's easier to find out) and one student told me they can't do it
What's the process to create tags? Is this simply a matter of having enough points to be allowed to do it?
Xavier, I believe you might have the rep needed to make the tag yourself. Once made, all the participants can select it (I think). If you can't someone with higher rep with civi could.
From a CiviCrm perspective, I think a civi-gsoc tag would be entirely appropriate as it is relevant and a civi-backed (not personal) project and thus part of the entire civi community.
However, it would not be appropriate for a company to make their specific tag, an instructor make a tag for their class or a student to make an individual tag for their individual project.
That said, gsoc people should understand this medium would be for questions and answers on difficulties with their project - not project updates or feature request feedback.
Yes, tags are created when they are needed on a question by folks with enough reputation to do so. You can also 'flag' the question and request the tag be created.
But we do not allow tags to be used for personal use in this manner. Tags are for the entire site to describe the subject of the question. Tags that describe some other aspect of the question are explicitly discouraged and will be removed. Sorry about the confusion. Please let me know if you have any further questions.