I happen to own some Bitcoins. But I also happen to be a person, who has never bought anything with them. Maybe this is partially because, officially, Bitcoin was not recognized as a currency in Canada or the USA. I bought the Bitcoins a long time ago, with the hope of watching their value increase – which it did – and then being able to continue owning them.
And we have a variety of Bitcoin Wallets to choose between. I began by choosing “Bitcoin Core” as my Wallet. This particular Bitcoin Client has as feature, to be able to support the Peer-2-Peer infrastructure, should other clients want to negotiate transactions, while mine is visible as a potential server for those to connect to. Further, I chose to set this one up “On A Zero-Trust Basis”. The way most Bitcoin Wallets work, they simply connect to a dedicated server, and accept whatever data that Peer offers. A Peer based on zero-trust cannot do that, but needs to find the first Bitcoin-transaction that ever occurred, and needs to download all the transactions that took place since then, to verify the integrity of all those blocks, and eventually to determine the integrity of our own Wallet.
(Edit 10/07/2016 : This is an option which Bitcoin Core gives us when we set it up for the first time. Not all the instances are set up this way, the alternative being the quicker, recommended, Automatic Connection option.)
Obviously, we would not choose to install it this way on our Smart-Phone, since it produces long delays if told to connect, after long periods of inactivity. And I did not choose this approach due to mistrust. I chose this approach, because it was the most powerful version of the software, still within my practical reach. And I still live in an era, where users want their computers to have far more power, than we really need. Further, this version of the software does not provide the user with a GUI, from which he could actually display all those anonymous transactions and Bitcoin-Addresses, as if to investigate them. But this also suits me well, as such a transaction history would be meaningless for me just to look at.
But if the need comes up, to migrate all the critical data off a Hard-Drive, let us say because the computer in question has become unstable, and if we have a Bitcoin Wallet on that HD, then we also need to transfer our Bitcoins, to a Wallet on another computer. This sounds straightforward, since one person can have as many Bitcoin Wallets as they wish, and can transfer the Bitcoins as though transferring chunks of gold, from one pouch to another.
But when I fired up my Bitcoin Wallet yesterday afternoon, around 13h00, I found out that it had fallen out-of-sync By 1 Year and 6 Weeks. It needed to recap the full transaction history that has taken place in the meantime, before giving me access to my own, meager Bitcoins.
And this happened to take, until 4h00 this morning. In the future, I will think twice before installing this one, particular type of Wallet. There are other Wallets available today, interesting in other ways.