The tendermint consensus engine records all agreements by a
supermajority of nodes into a blockchain, which is replicated among all
nodes. This blockchain is accessible via various rpc endpoints, mainly
/block?height= to get the full block, as well as
/blockchain?minHeight=_&maxHeight=_ to get a list of headers. But what
exactly is stored in these blocks?
The specification contains a detailed description of each component - that's the best place to get started.
To dig deeper, check out the types package documentation.