> For the complete documentation index, see [llms.txt](https://docs.feedspring.com/introduction/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.feedspring.com/introduction/core-concepts.md).

# Core Concepts

- [Feeds & Syncing](https://docs.feedspring.com/introduction/core-concepts/feeds-and-syncing.md): What a feed is, how FeedSpring keeps it updated, and how often content refreshes on each plan.
- [Posts & Fields](https://docs.feedspring.com/introduction/core-concepts/posts-and-fields.md): How FeedSpring structures feed data into posts and fields, and why that structure is the same across every delivery method.
- [Filtering](https://docs.feedspring.com/introduction/core-concepts/filtering.md): Filter which content a feed contains in the FeedSpring dashboard, for every delivery method at once.
- [Plans](https://docs.feedspring.com/introduction/core-concepts/plans.md): How many posts each feed holds, how often it refreshes, and the monthly view allowance on each plan.