I know the blockchain is the chain of blocks which contain transactions, a hash, and the hash of the previous block (Correct me if I'm wrong).
Correct. Among several other things.
Now, to 'create' a block do you just need transactions that don't fit in the previous one or you need to 'mine' it? The real question is how are blocks created? Do they need maintenance? Why?
Thanks
You always need mining to create blocks and include transactions.
Without going into too many details, once a transaction is included in a block, it cannot be included again in a new block. So yes, miners would need new transactions for a new block.
In order for a miner to earn the right to create a block they have to solve a mathematical puzzle called hashing.
The miners solve this hashing puzzle on the
header of the candidate block (the header is composed of block's version, time stamp, hash, previous hash, Merkle root of the included transactions, nonce, and difficulty target).
The miner who is lucky enough to solve this hashing puzzle is allowed to create the next block.
Once created and propagated, the block is accepted by the entire network (at least in principle) and the entire network maintains the integrity of that block and all the other valid blocks in the blockchain.
