files

banlist.dat: stores the IPs/Subnets of banned nodes

bitcoin.conf: contains configuration settings for bitcoind or bitcoin-qt

bitcoind.pid: stores the process id of bitcoind while running

blocks/blk000??.dat: block data (custom, 128 MiB per file); since 0.8.0

`blocks/rev000??.dat; block undo data (custom); since 0.8.0 (format changed since pre-0.8)

`blocks/index/*; block index (LevelDB); since 0.8.0

`chainstate/*; block chain state database (LevelDB); since 0.8.0

database/*: BDB database environment; only used for wallet since 0.8.0

db.log: wallet database log file

debug.log: contains debug information and general logging generated by bitcoind or bitcoin-qt

fee_estimates.dat: stores statistics used to estimate minimum transaction fees and priorities required for confirmation; since 0.10.0

mempool.dat: dump of the mempool's transactions; since 0.14.0.

peers.dat: peer IP address database (custom format); since 0.7.0

wallet.dat: personal wallet (BDB) with keys and transactions

.cookie: session RPC authentication cookie (written at start when cookie authentication is used, deleted on shutdown): since 0.12.0

onion_private_key: cached Tor hidden service private key for -listenonion: since 0.12.0