An SEO package is a defined bundle of search engine optimization work, such as technical fixes, on-page changes, content and link building, sold as a single plan with a set scope. Monthly SEO packages repeat that scope every month, so the work keeps going and builds up over time.
A package is different from hourly or one-off SEO work. You and the agency agree up front which tasks are covered, how many pages or locations are included and what gets reported. That shared scope lets you see what you are paying for and check each month's work against it.
Here is an example. A plumbing company with one location and a 20-page website might choose a package that covers fixing crawl errors, rewriting title tags and headings on its service pages, publishing one new article answering a common customer question, and updating its Google Business Profile. Each month, the company gets a report showing which of those tasks were completed.
Packages usually differ by size rather than by type of work. A larger package typically covers more pages, more locations, more content and more link outreach, because bigger sites and more competitive markets need more effort. A local package puts more weight on location pages and map listings. An ecommerce package puts more weight on category and product pages.
No package is best in general. The right one is the one whose scope fits your site's actual problems, which is why an SEO audit is a sensible first step. For a closer look at how tiers are usually structured, see our guide to how SEO packages work.