Do blockchains contain a websocket server?

Question

I was recently reading about blockchains and am very intrigued by this technology. I had a few questions regarding blockchains:

1. Do Blockchains use web-sockets to transmit information between users? If yes then is the information(blocks) sent always a JSON object?

2. Do all users have the entire copy of the blockchain, do they each just see a partial copy of the blockchain? if yes then how big can the file get?

3. Also, what determines transactions/second? I read bitcoin does about 7transactions/seconds and what is needed to make them more scalable, is it coding factors such as writing a more efficient algorithm (big-O) or is it some kind of hardware limitation?

Sorry if these questions seem trivial but I am a newbie trying to learn the technology. Any help would be appreciated.

Answer 1

I would prefer to answer your questions one after the other. 

• Usually, blockchain networks use some low-level protocol which is built on top of TCP for transmitting information between users. 
• Technically, users should have an entire copy of the blockchain for validating transactions. Although considering the vast size of Bitcoin (200 GB) and Ethereum (600 GB), some users use lightweight clients. However, they are not deemed to be a part of the distributed network in that case.
• In Bitcoin, the limit on block size is 1 MB. The average transaction size is about 400 bytes, therefore an average block contains 2000 transactions. There is no problem with increasing block size limit (we can say considering the Bitcoin Cash network whose size was increased to 32 MB), but we cannot increase it to infinity since we have finite internet connection speed and transaction verification disk/CPU resources.

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