As a rule, the keys are stored in an encrypted wallet.dat file (wallet), protected by a password.
The most popular wallets:
Bither,
GreenBits,
MultiBit HD,
Armory,
Blockchain,
mSIGNA,
Bitcoin Wallet,
Copay,
Coinbase,
Coinkite,
Circle Snapcar,
BitGo,
GreenAddress,
Hive,
Strongcoin,
Xapo,
Bitcoin Core,
Electrum,
Airbitz breadwallet,
Mycelium.
Bitcoin wallet on a computer
It is necessary to download the application. The keys are stored locally (unless HD wallet technology is used). There are such wallets:
thick - it is necessary to download the entire chain of blocks and download new ones (the most reliable option);
thin - it is not necessary to download full chains, so it is convenient to use on smartphones and tablets, but one hundred percent security is not guaranteed.
Online wallets for storing bitcoins
There is no need to download absolutely all network blocks, that is, time and device memory are saved. You can manage remotely (via the Internet), save addresses of other wallets, transfer bitcoins. Notifications are often provided.
There is a risk of hacking the service and stealing virtual money. Experienced users recommend storing small amounts in this option and for a short time.
Mobile wallets
They give access to bitcoins using iOS and Android devices. Technologies for reading and recognizing QR codes or NFC (Near Field Communication) are used.
Bitcoin Wallet is an offline wallet for Android. The balance is displayed in different formats and currencies. Addresses are saved. Allows you to pay via Bluetooth, sends notifications about the receipt of bitcoins.