Ah, info-dumps! The bane of fantasy writers the world over.
A large volume of data supplied at [one] time, says the internet.
Czech: informace o výpis
In writer terms:
A great wad of information on backstory placed at an inappropriate time and/or in an inappropriate manner.
What's the lure of this? You've spent all this time developing your world and you desperately want to let the reader know all about it!
Give it time.
Your readers are smart. They don't need to know everything from the beginning. The most important thing in the first three chapters is to hook your reader into the adventure.
Start where the story starts (more on this in another post) and stay relevant to the action.
The biggest info-dump offenders are prologues and first chapters (Ryan, I'm looking at you).
Yes, yes, I've written a prologue and in my old draft I had a nice, juicy info-dump. I can tell you now, my new first chapter is much stronger without the storyteller character, and without it being seven years before the story even starts.
Don't bother reading the next five hundred paragraphs unless you really want to. This is an example of an info-dump from my old draft -- in Chapter One -- and an example of what not to do. (It also involves the fantasy trope of the storyteller!)
Also, this was almost 70,000 words ago and I'm a much better writer!
Eight . . . hundred . . . and . . . fifty . . . four . . . unnecessary . . . words.
Why are info-dumps so bad? Because they slow down the real story, the story your readers are actually interested in.
How to Avoid Them
Stop! Reconsider before throwing them down in slews in the first three chapters. What your readers do need is grounding -- they need to know where the characters are, what they're doing and why. But of course, don't tell us these things (otherwise it would become an info-dump), but show us.
My new first chapter that I plan to write in my next draft, the main characters start out alone, hungry and desperate. But I don't want to go telling everyone why they're desperate. I'll show them instead. So in my first scene the MC will be sneaking into a house at night-time to steal a loaf of bread. That shows that they're desperately starving -- it doesn't need to be said
Later, we will find out through the dialogue of the characters that their father was taken away by the government. Or perhaps another way to approach this would be for the characters to have a discussion, which would then prompt a thought by the MC as to what had happened with the father.
And I think that's an important technique to take away from this.
Demonstrate your world-building through prompt.
When your character sees something for the first time in the book, that's a good time to throw in a line or a paragraph about it.
World-build to your heart's content; it can only make your world richer and truer. Just don't expect it all to get mentioned.