Written by Ayomide Abimbola

October 7, 2021



Blockchain is simply a chain of blocks that contains information. It records this 

information in a way that it will be impossible or difficult to change, hack or cheat the system.  

Blockchain is sometimes referred to as Distributed Ledger Technology (DLT). This is a protocol that enables the secure functioning of a decentralized digital database by allowing storage of information using cryptography.

Blockchain consists of four structures which are :

  1. Blocks
  2. Nodes
  3. Miners
  4. Wallet

Blocks – Every chain is made of multiple blocks and these blocks have three elements present which are 

  • The data in the block
  • Nonce – This is an abbreviation for “number used only once”. It is a 32-bit whole number. The nonce is randomly generated when a block is created which then generate a block header hash
  • Hash – This is a 256-bit number wedded to the nonce. This must start with a huge number of zeroes (that is very small)

When the first  block is generated, a nonce generates a cryptographic Hash. The data in the block is considered signed and forever tied to the nonce and hash unless mine takes place.

Node – This is any kind of electronic device which maintains copies of the blockchain and also keeps the network functioning.

There are of two types which are:

  • Full node
  • Partial node
  • Full Node – This maintains a full copy of all transactions made and it also has the capacity to validate, accept and reject transactions. 
  • Partial Node – This is also called Lightweight Node. This only maintains only the hash value of the transactions and doesn’t keep the whole copy of the blockchain ledger. This node has a low storage and low computational power, thus, maintains only the hash value of the transaction.

Miners – Miners create new blocks on the chain through a system called Mining.

 In a specific blockchain, every block has its own unique attributes (in terms of nonce and hash) but also references the hash on the previous block in the chain to create a new block. This makes mining a block not to be easy,especially on large chains.

Due to this difficulty,  miners make use of special softwares to solve a complex math problem of finding a nonce that generates an accepted hash.

The nonce is only 32 bits while the hash is 256 bits, this makes about 4 billion possible nonce-hash combinations that must be mined before the “golden nonce ” can be found and their block is added to the chain.

Peradventure, a change is considered to be done on a block, this will require not just re-mining the block with the chain but all of the blocks that come after it. This is why manipulation is extremely difficult in blockchain technology and when a block is successfully mined, the change is accepted by all the nodes on the network and the miner is financially rewarded.

Wallet – This is a digital wallet that allows storage of cryptocurrency. Every node in the blockchain has a wallet. Wallet focuses on these three main things

  • Privacy
  • Secured Transactions
  • Easy usage

The privacy of any wallet is maintained using public and private key pairs. Transactions are then made secure as a private key is needed to both send funds and to open the encrypted message.

There are two main types of wallet

  • Hot Wallet
  • Cold Wallet
  • Hot Wallet –  The Hot wallet is connected online and it is used for day-to-day transactions. Hackers can attack this type of wallet as it is connected to the internet.Hot wallets are further classified into two types 

a. Online-Web wallets –
These wallets run on the cloud platform. Examples are MetaMask Wallet and MyEtherWallet .

b. Software wallets – This consists of mobile and desktop wallets. Examples are Mycelium and Electrum respectively.

  • Cold Wallet-This type of wallet is not connected to the internet; hence it is very safe and hackers cannot attack it.

 This type of wallet can be purchased by the user. There are of two types of wallets which include:

a. Paper wallet – They are offline wallets in which a piece of paper is used that contains the crypto address. The private key is printed in QR code format. QR code is scanned for cryptocurrency transactions.

b. Hardware wallet – This stores users private keys in secure hardware devices. They act like a flash drive and it can be connected to a computer when you want to send Crypto. After completion of the transaction, it can be disconnected and kept cold again. Examples include Ledger Nano S, Trezor One.


Some websites which are referred to as blockchain explorers visualize transaction data from the blockchain. Here you can see all transaction data that have occurred or are occuring on the Blockchain irrespective of who you are or whether or not you have contributed on the blockchain.

The transaction details such as time the transaction took place, the volume involved and also the addresses can all be seen on the blockchain. Details about the sender cannot be seen as the whole transaction is done under the coverage of a bitcoin address.


  1. Go to the address

  1. Click on the explorer icon

  1. Next is to choose the type of wallet that needs to be explored either a Bitcoin wallet, an Ethereum wallet or various as seen in the picture below 

  1. We will be using a Bitcoin wallet in this article ‘1MoLDoRR2LGi2ok5YN5QfrefJCdWw8ynUm’ and we input the address in the search bar

  1. After searching, we have the following result

If we decide to check transactions on an Ethereum wallet (0x650de6baebb41a239813cb2bc148c7f82738e174) ,we navigate to the Ethereum Explorer and we input the address in the search bar 

After which we then obtain the following result 

Ethereum transactions can also be checked using the Etherscan

Using the Ethereum address above(0x650de6baebb41a239813cb2bc148c7f82738e174), we can also monitor transactions by inputting the address in the search bar and obtaining similar result as seen using

In conclusion, all transactions can be seen on a particular address being searched, but details like the name of the sender can not be seen. Other information about the sender like the address being used and time the transaction took place are all stored within the blockchain.

Written by: Abimbola Ayomide © Crypto University 2021

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