By dictionary definition, a craft is a branch of a profession or occupation, usually a membership in a group or guild, which requires some particular kind of skilled work. In the case of the craft of writing, it is a career or occupation, not simply a hobby, which requires artistic skill. Writing also requires commitment.
The craft of writing is learning the proper elements of writing: writing technique, grammar, and style. This includes structure, formatting, clarity, and in fiction writing, plot, character development, point of view, and dialogue. In writing poetry the elements are form, lines, stanza, rhymes and rhythm (meter), pattern, and euphony and then there are the literary devices. Writing non-fiction, which conveys factual information, refers to people, places, events and things. Creative non-fiction uses elements of the literary craft, specifically the techniques of ﬁction writers, playwrights, and poets.
There are many other types of writing with specific elements, such as playwriting, scriptwriting for film and television, academic, journalistic, online, business, advertising and promotional writing, which you can research. It’s important to research elements fully as a fundamental basic to the craft of writing. It’s also vital to know the particulars in the genre or sub-genre in which you write. There is a great deal of information available from many sources including books and the internet.
“Being a writer means you need to learn the craft of writing, and continue honing your skills.” - From Being a Writer - Learn the Craft of Writing at Writers on the Move