Lesson 9 — Pagination

One page at a time

Pagination splits a long list into pages. With a page size of 2, page 1 is items 0–1, page 2 is items 2–3, and so on. The slice for page p starts at (p - 1) * size and stops at p * size:

items[2:4]   # page 2 when size is 2

Django has a Paginator class that does exactly this math for you.

Note: the exercise runs in your browser without Django installed, so it is a small plain-Python simulation of what Django does for you.

Why it matters: nobody can load 10,000 products at once — pages keep sites fast.