What does “up through” mean?

Question

I'm a newbie in English. While I was reading a book, I found that phrase in "(something) will be the topic of the following chapters up through Chapter 3.", but I don't understand what it means.

Answer 1

Up here names the direction of reading. Presumably the author thinks of readers 'ascending' from Chapter 1 to Chapter 2 to Chapter 3 ... going up the scale of numbers.

Up is really superfluous here—but colloquially we US speakers are getting fonder and fonder of giving our utterances a little extra dynamism with prepositions like that, and the use is common in all but the most formal styles these days.

Through names the 'distance' of reading during which the topic will be in the foreground: not to Chapter 3, which would imply that when the reader gets to Chapter 3 the topic will change, but through Chapter 3, all the way to the end of Chapter 3.

Answer 2

Example: I played baseball up through college and university.

The phrase 'up through college and university' means throughout the whole time you were in those places. Notice the following.

1. I worked as a lawyer up through 2006.
2. I lived in Boston up through sixth grade.

So, 'up through' means 'throughout'.

"(something) will be the topic of the following chapters up through Chapter 3" means that topic will be approached throughout Chapter 3, from the beginning to the end.