Bitcoin Forum

I am introducing my friend to bitcoin, i figured we need more people into bitcoin, and hes a techy guy also, so it's easy to explain.

But the problem is he doesn't have unlimited internet. So the Bitcoin core-client is out of the question.

What can i start him off with?  I was thinking about Electrum, because you don't have to download the blockchain.

Is electrum safe? Or come someone steal his bitcoins,  I'm not too familiar with it, I downloaded it today and playing around with it.


Any advice?

Electrum is very safe, and for people who don't want to download the full blockchain, it is one of the best clients to use.

Electrum is safe enough, go ahead, use it in a safe environment, you can use also in mobile for iOS or Android. https://electrum.org/#download

That's great,

What i don't understand is,  the blockchain,

Why does bitcore client need the blockchain, and electrum doesnt need the blockchain.

In fact, i am now very confused,  What exactly is the purpose of the blockchain, and why doesnt electrum need it

Bitcoin Core is a full node. This means that it fully verifies and validates every single transaction and block that it receives. In order to do that, it must know the entire history due to the chaining, so it must download the entire blockchain. Actually, with 0.12, while it still needs to download the entire blockchain, if pruning is enabled, it does not need to store the entire blockchain.

Electrum (and many other wallets like MultiBit) is an SPV wallet. This means that it relies on someone else to provide it the proper information. SPV wallets rely on full nodes to validate the transactions and blocks and then the wallet requests only the information that is relevant to it. It is unable to fully validate and verify blocks and transactions because it does not have the full history. This means that SPV nodes are slightly less safe because you need to trust someone else to provide the right information. In general, SPV wallets are still very safe.

i suggest you read the Electrum documentation here: http://docs.electrum.org/en/latest/ it answers almost all of your questions.
some good information about SPV : https://en.bitcoin.it/wiki/Thin_Client_Security

some extra info:
what you need to download once apart from the wallet itself is called "blockchain_headers" which is <30 MB after that each time the wallet synchs it receives a very small amount which is suitable for limited bandwidth, and slow connections.

Electrum is a great client to start with.
When you introduce your friend to Electrum please make sure that he writes down the seed and keeps it at a safe place.