Things are compared with other things to:
1. give them a deeper meaning
2. explainations
3. To show similarites
It can best be described as the writer's opinion
<span />
The answer to your question would be prohibited as it does mean to be forbidden or not allowed to and on this sentence is saying that since it was too noisy it was impossible to study.
Answer:
Blockchain technology or A blockchain
Explanation:
"Every time a person makes a transaction using a cryptocurrency — for example, using funds stored in his or her crypto wallet to send bitcoin to someone else — the transaction is recorded on a digital ledger called a blockchain."
Please feel free to comment, ask questions, give feedback, and correct me if I am wrong!
Have a great day!
:)