Anonymity of the spender with bitcoin I know an important feature for digital cash (in contrast to credit cards transaction) is anonymity of the users: when I spend a digital coin in exchange of goods or services, I would like not to disclose any identity information to the provider of such goods or services, just like when I go to a common shop and pay cash.

Now my questions are: 


Does Bitcoin achieve this kind of property (anonymity of the Spender)?
If yes, how?
Actually there are "addresses" in bitcoin. You have an address and associated transactions (equivalent to the amount of satoshis you have). When you want to spend these bitcoins, you create a transaction where it says : "the destination address" to which you pay. 
To have a bitcoin address, you do not need to give personal data, you only have one address (a hash) and the public and private key that make you owners of that address.
It is this procedure that offers you anonymity, but all these transactions are stored in plain text on all nodes in the network.