A trailblazer is a person who does something first, before anyone else has shown the way — a new method, a new kind of job, a new idea — and by doing it makes it possible for the people who come after. The picture behind the word is very physical: someone walking into a forest where there is no path yet, cutting marks into the trees so that others can follow the same route later. That second half matters. We do not usually call someone a trailblazer just because they were early or unusual; we call them a trailblazer because other people came after them along the road they opened. A woman who becomes the first female judge in her country, a scientist who opens a whole new field of research, a small company that sells something in a way nobody had tried — these are trailblazers. The word is warm. It is praise, and quite strong praise, so it turns up a lot in news writing, in speeches, in obituaries, and on company websites. Because it is used so freely there, it has worn a little thin — a firm may call its own product "trailblazing" when it is only mildly new — and a careful reader hears that as advertising rather than fact. In everyday speech it is not very common; you would more likely say someone was "the first to do it". You can also use it lightly and half-jokingly among friends ("you're a real trailblazer" to someone who ordered a strange thing on the menu first), and the joke works precisely because the real word is so grand.