What is a Blockchain Explorer and Difficulty?

Please note: This is a supplement to the “Blockchain and Cryptocurrency Explained” series. If you want to start from the beginning, go here.

Blockchain explorer is one of the essential tools in any cryptocurrency. These explorers provide information on the status of the blocks, transactions and currency. We will cover some of the basic information related to blockchain explorers.

Let’s take two currencies side by side to understand this completely:

  1. Bitcoin Blockchain Explorer – https://blockchain.info/
  2. Ethereum Blockchain Explorer – https://etherscan.io/

Network Status

We can find out how the network is doing by looking at the below stats. Each piece of information can help us understand the currency better as whole.

Blockchain length

The height or last block number tells you the current blockchain length. If the height or last block is 100, then the current blockchain length is 100.

A longer chain means it is more secure.


Bitcoin Blockchain explorer Homepage



Etherscan Blockchain explorer Homepage


The amount of computing power being utilized on the cryptocurrency network. This is normally denominated as H/s or hashes per second. It can be GH/s for giga-hashes per second or TH/s for tera-hashes per second

If you remember our discussion on the email and Hashcash, computer needed to try every combination to find the correct combination and hash. Same formula applies here. So, when it shows that the network hashrate is:

1 GH/s or 1 Gigahashes per second → Computers are trying 1 billion combinations (or hashes) each second to try and find the correct combination

We want the hashrate to be higher as it will mean there are a lot of computers working on securing the cryptocurrency.


Info is there on status page (https://blockchain.info/stats):

Bitcoin Blockchain Hashrate


Ethereum Blockchain Hashrate


Mining Difficulty

Cryptocurrencies need to ensure coin distribution is fair. Most of the coin supply is from block rewards (check part 4). So, cryptocurrencies tend to have an average block generation time. Bitcoin’s is 10 minutes. Every time a block is generated before 10 mins it will increase the mining difficulty. The process of changing the difficulty is referred to as difficulty adjustment. 


This can be found on status page (https://blockchain.info/stats):

Bitcoin Blockchain Difficulty


Ethereum Blockchain Difficulty

Each currency has it’s own way of expressing difficulty. Ethereum is denoting as number of hashes required while bitcoin doesn’t. Not going into technical details, higher is always better as it will mean more people are mining and securing the cryptocurrency.

What is difficulty?

To understand let’s take a hypothetical example on Hashcash. There we said a hash with starting 20 bits being zero might take a second. So suppose we have a coin using the basic Hashcash. The block generation time is 2 seconds. This will happen step by step:

  1. First block is generated in a second.
  2. Cryptocurrency sees that and enforce rule by changing “difficulty”. Now the requirement is to find hash with 40 bits ie 2 seconds.
  3. Second block is generated in 2 seconds.
  4. Third Block is generated in 1.5 seconds. People want more coins and quickly! So they use more computing power and reduce time.
  5. Cryptocurrency adjusts the difficulty again to ensure 2 seconds. It will change the rule to 80 bits.
  6. Fourth block is generated in 3 seconds. Now there is not enough computing power to complete the hash in 2 seconds.
  7. Cryptocurrency adjusts the difficulty again to ensure 2 seconds. It will change the rule to 60 bits
  8. Fifth block is generated in 2 seconds.
  9. Sixth block is generated in 1.5 seconds.
  10. Cryptocurrency adjust…. you get the idea…

Block Generation Time

The statistics for generation time can also be found.


Info on status page (https://blockchain.info/stats):

Bitcoin Blockchain Generation Time


Ethereum Blockchain Generation time

Fun fact: You can look at Ethereum’s difficulty and hashrate to arrive at the average time. Here’s the calculation:

HashRate = 86785.40 GH/s

Difficulty = 2159.71 TH = 2159.71 * 1000 GH = 2159710

Average Time = Difficulty divided by Hashrate = 2159710/86785.4 = 24.78 seconds

Note on mining

While I said high hashrate and difficulty is good for a currency. It also has an inverse effect on mining. Most of the currencies are unmineable by Average Joe because there are now specialized hardware and software miners which work even in these extreme conditions. Only when you find a coin with less hashrate or difficulty should you think about pool mining. Nowadays, you shouldn’t solo mine.

Block Information

Blocks are the basic building blocks of any cryptocurrency. All transaction and identity information is stored in the blocks. Blockchain explorers provide a for us to see any block in the chain. It can be as far as the very first block in the chain to the newest blocks.

Block Search

We can search for any block from the homepage or you can click on the most recent blocks.


Bitcoin Blockchain explorer Homepage

482434 is the recent block. You can click to see the block information. While you can search for the block number above.


Etherscan Blockchain explorer Homepage

4215359 is the recent block. You can click to see the block information. While you can search for the block number in the search box.

Block Information Content

Once you click on the blocks you can see all the relevant information. The information structure will depend on the explorer as well as coin characteristics.


Bitcoin Blockchain Block Info

Some of the details of the block are:

  1. The block number or height
  2. Output total – The total number of balances after the transactions (total of all the green highlight)
  3. Estimated Transaction Volume is the amount of transactions within the block
  4. Transaction fees which goes to the miner finding the block
  5. Time of addition of the block
  6. Relayed by shows the miner of the block – Here it is a mining pool
  7. Difficulty of mining the block
  8. The block reward which is currently 12.5 BTC
  9.  “No Inputs” shows the total block reward. (12.5 BTC per block+ 3.87 BTC in fees ~ 16.37 BTC)
  10. Transactions contained in the block along with the addresses
  11. Hash of this block as well as the previous and next block


Ethereum Blockchain Block Info

Here you find nearly the same information as above. Some of the ethereum specific details are:

  1. Ethereum allows people to write digital contracts. Hence there is a separate section for contracts as well
  2. Fees is knwon Gas in ethereum
  3. Uncle reward – Think of these as block rewards as well
  4. Block reward is already broken down to Reward + fees. There are two entries for fees related to transactions and contracts

You can click the transaction link to see all the transactions and associated:

Putting this all together:

  1. Transaction fees can give you an idea on cost associated with doing a transaction. Example bitcoin from above. Total fees are nearly 3.88 BTC and Total number of transactions = 2309. So, the average fees is 3.88 BTC/ 2309 = 0.00168 BTC. You can do a lot of similar calculation to see how well the fees are working.
  2. More active coin means more number of transactions as well as volume of transactions.
  3. It is necessary to see the difficulty of blocks, specially the early ones. We will discuss the impact in next blog.
  4. Block reward tells you the number of coins given for finding a block.

Account Information

Blockchain being a public ledger, you can also find all the account information too. Just input the account address in the search box mentioned above. Address summaries look like this:


Bitcoin Blockchain Account Info

Details here are:

  1. Transaction Hash (green box)
  2. Address
  3. Number of transactions from this account
  4. Total received in the account
  5. Current balance of the account
  6. All transactions of this account (Green arrows shows BTC coming into the account and Red show BTC going out)


Ethereum Blockchain Account Info

Most of the information is similar. Differences are:

  1. Out and In mark outgoing and incoming transactions respectively.
  2. Token balances show the Ethereum tokens held by the account
  3. Token transfers are under the tab “Token Transfers”

Transaction Information

You can also check any transaction you want. These are clicking the transaction hash in:

  1. Block information
  2. Account information


Bitcoin Blockchain Transaction Info

Skipping the technical information here, what we can see is:

  1. Transaction amount
  2. Fees paid for this transaction


Ethereum Blockchain Transaction Info

Information here is similar. Ethereum goes into a lot of detail about “Gas” or fees as this has been a concern among people wanting to use cryptocurrencies. So, it not only tells you the exact fees but also the exact fees required. So here it costs $0.15 for each ether ($357).

Next blog will cover the how to use what we have learned here to find out talk about fraud coins.


Also published on Medium.