After a site reorg you need old links to keep working. Reach for return for fixed paths and rewrite only when you must capture part of the URL.

One page moved — exact match, cheapest:

location = /old-page {
    return 301 /new-page;
}

A whole section moved — capture the rest of the path with rewrite:

# /blog/anything  ->  /articles/anything
rewrite ^/blog/(.*)$ /articles/$1 permanent;

permanent means 301; redirect means 302. The $1 is the captured group. rewrite keeps the query string automatically unless you end the replacement with ?.

Redirect to another domain, preserving the path:

location /docs/ {
    return 301 https://docs.example.com$request_uri;
}

Add or remove a trailing slash consistently:

# Force a trailing slash on a known directory-style path:
location = /shop {
    return 301 /shop/;
}

Guidance:

Prefer return — it’s explicit and fast. Use rewrite only for pattern captures.
rewrite ... last re-runs location matching (internal rewrite, no redirect sent); rewrite ... permanent/redirect sends a real 3xx to the browser. Don’t confuse them.
Avoid if for redirects where a location will do — location matching is clearer and avoids if edge cases.
Verify without a browser cache getting in the way:

curl -sI https://example.com/blog/hello | grep -i location
# location: https://example.com/articles/hello

Redirect old URLs to new ones