Implementation of the types and their (de-)serialisation via SCALE codec.
On the Rust side, the codec types and primitive types are implemented via the parity-codec.

Codec types

These are the base types of the codec. They are typically not used directly, but rather inherited from to create specific types. They are the building blocks for declaring custom types:

Types
AbstractArray	Manages codec arrays. It is an extension to Array
Base	A type extends the Base class, when it holds a value
Compact	A compact length-encoding codec wrapper. Mostly used by other types to add length-prefixed encoding
Enum	A codec wrapper for an enum. Enums are encoded as a single byte, where the byte is a zero-indexed value
Int	A generic signed integer codec
Option	An Option is an optional field. The first byte indicates that there is is value to follow
Set	An Set is an array of string values, represented an an encoded type by a bitwise representation of the values
Struct	A Struct defines an Object with key-value pairs - where the values are Codec values.
StructAny	Wraps the a JSON structure retrieve via RPC. It extends the standard JS Map
Tuple	A Tuple defines an anonymous fixed-length array, where each element has its own type
U8a	A basic wrapper around Uint8Array. It will consume the full Uint8Array as passed to it
U8aFixed	A U8a that manages a a sequence of bytes up to the specified bitLength
UInt	A generic unsigned integer codec. It handles the encoding and decoding of Little Endian encoded numbers in Substrate
Vec	This manages codec arrays. Internally it keeps track of the length (as decoded)
VecAny	This manages codec arrays, assuming that the inputs are already of type Codec

Primitive types

These primitive types are available:

Types
AccountId	A wrapper around an AccountId/PublicKey representation
AccountIndex	A wrapper around an AccountIndex, which is a shortened, variable-length encoding for an Account
AccountInfo	An Account information structure for contracts
Address	A wrapper around an AccountId and/or AccountIndex that is encoded with a prefix
Bool	Representation for a boolean value in the system
Bytes	A Bytes wrapper for `Vec<u8>`
Call	Extrinsic function descriptor, as defined in the extrinsic format for a node
Data	A raw data structure. It is an encoding of a U8a without any length encoding
Event	Wrapper for the actual data that forms part of an Event
EventRecord	A record for an Event (as specified by Metadata) with the specific Phase of application
Extrinsic	Representation of an Extrinsic in the system
ExtrinsicEra	The era for an extrinsic, indicating either a mortal or immortal extrinsic
ExtrinsicSignature	A container for the Signature associated with a specific Extrinsic
H160	Hash containing 160 bits (20 bytes), typically used in blocks, extrinsics and as a sane default
H256	Hash containing 256 bits (32 bytes), typically used in blocks, extrinsics and as a sane default
H512	Hash containing 512 bits (64 bytes), typically used for signatures
Hash	The default hash that is used accross the system. It is just a thin wrapper around H256
I8	An 8-bit signed integer
I16	A 16-bit signed integer
I32	A 32-bit signed integer
I64	A 64-bit signed integer
I128	A 128-bit signed integer
I256	A 256-bit signed integer
Moment	A wrapper around seconds/timestamps. Internally the representation only has second precicion (aligning with Rust)
Null	Implements a type that does not contain anything (apart from `null`)
Origin	Where Origin occurs, it should be ignored as an internal-only value
Signature	The default signature that is used accross the system
ExtrinsicPayload	A signing payload for an Extrinsic. For the final encoding, it is variable length based on the contents included
StorageData	Data retrieved via Storage queries and data for key-value pairs
StorageKey	A representation of a storage key (typically hashed) in the system
Text	This is a string wrapper, along with the length.
Type	This is a extended version of String, specifically to handle types
U8	An 8-bit unsigned integer
U16	A 16-bit unsigned integer
U32	A 32-bit unsigned integer
U64	A 64-bit unsigned integer
U128	A 128-bit unsigned integer
U256	A 256-bit unsigned integer
USize	A System default unsigned number, typically used in RPC to report non-consensus data
Weight	Numeric range of a transaction weight.
WeightMultiplier	Representation of a weight multiplier. This represents how a fee value can be computed from a weighted transaction.

Substrate types

These custom types implement specific types that are found as part of the Substrate core. They're all extensions of one of the codec types:

Types
Amount	The Substrate Amount representation as a Balance
ApprovalFlag	Approval flag, implemented as a U32
AssetOf	The Substrate AssetOf representation as a Balance
AuthorityId	Wrapper for a AuthorityId. Same as an normal AccountId
AuthoritiesChange	Log for Authories changed
AuthorityWeight	The weight of an authority
Balance	The Substrate Balance representation as a U128
BalanceLock	The Substrate BalanceLock for staking
BalanceOf	The Substrate BalanceOf representation as a Balance
BlockNumber	A representation of a Substrate BlockNumber, implemented as a U64
CodeHash	The default contract code hash that is used accross the system
Conviction	A value denoting the strength of conviction of a vote.
Consensus	Log item indicating consensus
ContractInfo	The contract information for a given contract
ContractStorageKey	A representation of a storage key for contracts
EraIndex	A representation for the era count
Exposure	A snapshot of the stake backing a single validator in the system
Gas	A gas number type for Substrate, extending U64
Heartbeat	Heartbeat which is send/received.
IndividualExposure	The Substrate IndividualExposure for staking
InherentOfflineReport	Describes the offline-reporting extrinsic
Justification	A generic justification as a stream of Bytes, this is specific per consensus implementation
Key	The Substrate Key representation as a Bytes (`vec<u8>`)
Keys	The session keys for both Grandpa (ed25519) and Babe (sr25519)
KeyValue	KeyValue structure. Since most of the keys and resultant values in Subtrate are hashed and/or encoded, keys and values are reprsented as Bytes
KeyValueOption	A key/value change. Similar to the KeyValue structure, but the value can be optional
LockIdentifier	The Substrate LockIdentifier for staking
LockPeriods	A number of lock periods
MemberCount	A number of council members
MisbehaviorKind	An EnumType containing a Bft misbehaviour
MisbehaviorReport	A Misbehaviour report of MisbehavioirKind against a specific AuthorityId
NewAccountOutcome	Enum to track the outcome for creation of an AccountId
NextAuthority	The next authority available as SessionKey
Nonce	The Nonce or number of transactions sent by a specific account
NonceCompact	The Compact or number of transactions sent by a specific account
OpaqueKey	A key represented as a Bytes
Perbill	Parts per billion (see also Permill)
Permill	Parts per million (See also Perbill)
PrefabWasmModule	Struct to encode the vesting schedule of an individual account
PropIndex	An increasing number that represents a specific council proposal index in the system
Proposal	A proposal in the system. It just extends Call (Proposal = Call in Rust)
ProposalIndex	An increasing number that represents a specific council proposal index in the system
ReferendumIndex	An increasing number that represents a specific referendum in the system
ReferendumInfo	Info regarding an ongoing referendum
RewardDestination	A destination account for payment
Schedule	Definition of the cost schedule and other parameterizations for wasm vm
Seal	Log item indicating a sealing event
SeedOf	The Substrate SeedOf representation as a Hash
SessionIndex	Simple index type with which we can count sessions as U32
SessionKey	Wrapper for a SessionKey. Same as an normal AuthorityId, i.e. a wrapper around publicKey
SetIndex	Set index, implemented as a U32
StakingLedger	The ledger of a (bonded) stash
StoredPendingChange	Stored pending change for a Grandpa events
StoredState	Current state of the GRANDPA authority set. State transitions must happen in the same order of states defined below, e.g. `Paused` implies a prior `PendingPause`
TreasuryProposal	A Proposal made for Treasury
UncleEntryItem	Information about an uncle to include
UnlockChunk	Just a Balance/BlockNumber tuple to encode when a chunk of funds will be unlocked
ValidatorId	Validator in the system, maps to an AccountId
ValidatorPrefs	Validator preferences
VestingSchedule	Struct to encode the vesting schedule of an individual account
Vote	A number of lock periods, plus a vote, one way or the other
Votes	Info for keeping track of a council motion being voted on.
VoteIndex	Voting index, implemented as a U32
VoterInfo	The activity status of a voter.
VoteThreshold	Voting threshold, used inside proposals to set change the voting tally
WithdrawReasons	The Substrate WithdrawReasons for staking

Polkadot types

These types are only available in Polkadot chains -

Types
AuctionIndex	A parachain auction index as a U32
AttestedCandidate	An attested candidate
Bidder	The desired target of a bidder in an auction.
LeasePeriod	The length of the lease for a parachain
LeasePeriodOf	The length of the lease for a parachain
IncomingParachain	Information regarding a parachain that will be deployed.
NewBidder	A bidder identifier, which is just the combination of an account ID and a sub-bidder ID. This is called `NewBidder` in order to distinguish between bidders that would deploy a new parachain and pre-existing parachains bidding to renew themselves.
ParachainDispatchOrigin	Which origin a parachain's message to the relay chain should be dispatched from.
ParaId	Identifier for a deployed parachain implemented as a U32
ParaIdOf	Identifier for a deployed parachain implemented as a U32
SlotRange	A compactly represented sub-range from the series (0, 1, 2, 3)
SubId	A sub-bidder identifier. Used to distinguish between different logical bidders coming from the same account ID.
UpwardMessage	A message from a parachain to its Relay Chain
WinningData	Winning data type. This encodes the top bidders of each range together with their bid.
WinningDataEntry	And entry in the WinningData fixed vector

RPC types

These types are not used in the runtime, but are rather used in RPC results:

Types
Block	A block encoded with header and extrinsics
ChainProperties	Wraps the properties retrieved from the chain via the `system.properties` RPC call
Digest	A Header Digest
DigestOf	A Header Digest
DigestItem	A EnumType the specifies the specific item in the logs of a Digest
ExtrinsicStatus	An EnumType that indicates the status of the Extrinsic as been submitted
Header	A Block header
Health	A system health indicator, reported back over RPC
NetworkState	Wraps the properties retrieved from the chain via the `system.network_state` RPC call
Metadata	The versioned runtime metadata as a decoded structure
PeerInfo	A system peer info indicator, reported back over RPC
RuntimeVersion	A Tuple that conatins the ApiId and U32 version
SignedBlock	A Block that has been signed and contains a Justification
StorageChangeSet	A set of storage changes. It contains the Block hash and a list of the actual changes

Derive types

These types are are specific for the Polkadot-JS derive API, so you won't find a representation of them in the SCALE codec or the Substrate core. They are used in the api-derive methods.

Types
HeaderExtended	A Header header with an additional `author` field that indicates the block author]