I will make a question as well:
What are SPV wallets and why are they important? Best and complete answer 3 merits.
In section 8 of the whitepaper, Satoshi talked about Simplified Payment Verification (SPV):
It is possible to verify payments without running a full network node. A user only needs to keep a copy of the block headers of the longest proof-of-work chain, which he can get by queryingnetwork nodes until he's convince he has the longest chain, and obtain the Merkle branchlinking the transaction to the block it's timestamped in. He can't check the transaction forhimself, but by linking it to a place in the chain, he can see that a network node has accepted it,and blocks added after it further confirm the network has accepted it.
From this, SPV wallets can be defined as those wallets that download a small, specific part of blockchain only but still make sure your transactions in block and maintain security (less secured than running a full node, of course). This kind of wallet is important because they're an ideal option for portable devices like smartphones.
