21Relay
Back to Self-Custody

Lesson 1 · Wallet Fundamentals

Bitcoin wallet types

A Bitcoin wallet manages private keys and helps you create, receive and sign transactions. Different wallet types balance convenience, security, privacy and recovery in different ways.

Beginner lesson8–10 minute readCompare before choosing

Wallets in simple terms

A wallet manages keys, not coins

Bitcoin does not sit inside a wallet application or hardware device. Bitcoin ownership is recorded on the blockchain.

A wallet manages the private keys that allow you to authorise transactions. It also generates receiving addresses, tracks balances and helps you review payments.

The most important question is not where the app is installed. It is who controls the keys and how those keys can be recovered.

Core idea

The wallet is the tool. The private keys are what provide control over the bitcoin.

Private key

Authorises spending

A private key is secret information used to sign Bitcoin transactions. Anyone who obtains it may be able to spend the associated funds.

Wallet

Organises and uses keys

A wallet helps generate addresses, monitor transactions and sign payments using the underlying private keys.

Hot versus cold

Convenience and isolation

Hot wallet

Connected and convenient

A hot wallet operates on an internet-connected device. It is easier to access but has a larger attack surface.

Mobile wallets

Desktop wallets

Browser wallets

Wallets connected to online services

Cold storage

Separated from online devices

Cold storage keeps signing keys away from normal internet-connected environments and is commonly used for long-term savings.

Hardware wallets

Offline signing devices

Air-gapped computers

Properly secured physical backups

A hardware wallet is often described as cold storage, but the complete security of the setup also depends on backups, transaction verification and how the device is used.

Wallet categories

Common Bitcoin wallet types

Mobile wallet

A wallet app installed on a smartphone. Mobile wallets are convenient for smaller balances and regular payments.

Everyday spending

Best for

Everyday spending

Connection

Usually online

Key control

Can be self-custodial

Strengths

Convenient and portable

Easy to scan payment QR codes

Suitable for smaller amounts

Risks

Phone loss or damage

Malicious apps or compromised devices

Less suitable for large long-term holdings

Desktop wallet

Wallet software installed on a desktop or laptop computer. It can offer more control and advanced features.

Regular desktop use

Best for

Regular desktop use

Connection

Usually online

Key control

Can be self-custodial

Strengths

Larger screen for transaction review

Can connect to your own Bitcoin node

Often supports advanced wallet features

Risks

Computer malware

Unverified software downloads

Device failure without a backup

Hardware wallet

A dedicated signing device designed to keep private keys separated from a general-purpose computer or phone.

Long-term savings

Best for

Long-term savings

Connection

Keys remain isolated

Key control

Self-custodial

Strengths

Private keys remain on the device

Transaction details can be checked on-device

Reduced exposure to computer malware

Risks

Supply-chain tampering

Incorrect recovery backup

Blindly approving a malicious transaction

Paper backup

A physical written or printed record of recovery information. This is a backup method, not a complete wallet experience.

Recovery backup

Best for

Recovery backup

Connection

Offline

Key control

Depends on storage

Strengths

Not connected to the internet

Simple to create

Useful as one recovery copy

Risks

Fire, water and physical damage

Loss or theft

Easy to copy incorrectly

Multisignature wallet

A wallet that requires more than one private key to authorise a transaction.

Advanced security

Best for

Advanced security

Connection

Depends on setup

Key control

Distributed control

Strengths

Reduces single points of failure

Keys can be stored in separate locations

Useful for shared or high-value custody

Risks

More complex backups

More difficult recovery

Poor setup documentation can cause loss

Custodial account

An exchange or service holds the keys on your behalf. You have an account balance rather than direct control of the private keys.

Trading and temporary access

Best for

Trading and temporary access

Connection

Service controlled

Key control

Third-party custody

Strengths

Simple account recovery

Easy trading access

No seed phrase management

Risks

Withdrawal restrictions

Company failure or insolvency

Account compromise or seizure

Custodial account

A company controls the keys

You depend on the service to approve withdrawals, protect the funds and remain operational.

Self-custodial wallet

You control the keys

You can authorise transactions independently, but you are responsible for security and recovery.

A wallet can be an app, desktop program or hardware device. The key distinction is whether you or a third party controls the private keys.

Choosing a wallet

Match the wallet to the purpose

There is no single wallet that is best for every person or every amount. A sensible setup may use more than one wallet for different purposes.

How often will you spend?

Frequent spending may suit a mobile or desktop wallet. Long-term savings usually benefit from stronger isolation.

How much are you protecting?

Larger balances justify more time, stronger backups and more careful recovery planning.

Do you understand the recovery process?

Do not store significant funds until you can confidently explain how the wallet is recovered.

Can the wallet connect to your own node?

A wallet connected to your own node can improve privacy and independent verification.

Can you verify transaction details?

The wallet should make it easy to check addresses, amounts and fees before signing.

Spending wallet

Small balance and convenient access.

Savings wallet

Stronger isolation and carefully tested recovery.

Node-connected wallet

Improved privacy and independent verification.

Warning signs

Stop before entering recovery information

The wallet asks you to type a seed phrase into a website

The device arrives with a recovery phrase already created

The software is downloaded from an unofficial source

The wallet claims funds cannot be recovered without the company

The app pressures you to act quickly

The product hides how keys are created or stored

Lesson summary

The important points

A wallet manages keys and transactions; it does not physically hold bitcoin.

Hot wallets prioritise convenience, while cold storage prioritises isolation.

Mobile, desktop and hardware wallets can all be self-custodial.

A custodial account means a third party controls the keys.

The most suitable wallet depends on the amount, purpose and recovery plan.

Never enter a seed phrase into a website or untrusted application.