Introductions

I can see what you mean, Kelby. That would be my ideal introduction too.
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No, I mean, that about spoilers. Thanks to that wonderful expendable introduction to Barchester Towers which I read after I had ended the novel, I now know what happens in The Last Chronicle of Barset to Mrs Proudie, the bishop's wife. The Last Chronicle is the fourth novel after BT and is the last of the series! Why do you want to do that? Not that I'm bothered personally, but it is no secret that a lot of people are.
To me it was as if this person was telling me, 'Surely you're not reading this thing for the first time?' or something.

Telling spoilers of that particular novel is one thing (you can avoid that by reading it later), telling spoilers of another is another thing, because that way you will have to skip all introductions and miss all the interesting bit in case a moron decides to put spoilers of other novels into his introduction to the one you're reading.

Even if they do feel the need to spoiler other novels, they could at least give a heads up at the start. I guess it makes sense that there would be spoilers if they're talking about how the book fits into the author's other books but a heads up would be nice.

aren't introductions called preface too?

I thought a preface was written by someone else about how the novel came about. It's not supposed to be an analysis at any rate. I might be wrong though, it's a while ago that I looked it all up to be certain I had the right word for a translation ;).

I agree about the spoilers.

A Preface is generally an introduction written by the author of the work themself. Historically, they would be an analysis of the work and the theory behind it, some authors like Shaw wrote extensive prefaces to all of their works (Wordsworth's Preface to the Lyrical Ballads is maybe the most famous preface). Although, I think I've noticed lately that prefaces are increasingly referred to as "an introduction by the author" in reprints of works.

Sometimes they use their prefaces as manifestos. Ironically Hugo's preface to Cromwell is more well-known than the actual play.