Personal information and bitcoin purchasing I am in the process of buying bitcoins and am being required to put in a lot of personal details. Once i buy the bitcoins is there any way that the information i had to submit to buy them originally can be traced back? thanks.
I am in the process of buying bitcoins and am being required to put in a lot of personal details.


The Bitcoin network itself requires no identifying information from users. In fact, efforts have been made to make transactions / addresses as indistinguishable from one-another as possible, in order to provide the best fungibility and privacy for users of the system. 

That said, many of the services which allow users to trade Bitcoins for fiat are businesses that are subject to the laws and regulations of the jurisdictions they exist and operate in. There are anti-money-laundering (AML) and know-your-customer (KYC) regulations in many jurisdictions that require these businesses collect information about their customers. In order to be a customer of one of those services, you must surrender personally identifying information. 


  Once i buy the bitcoins is there any way that the information i had to submit to buy them originally can be traced back? 


Lets consider two situations: 

a) You send all your personal info to an exchange, buy 1 bitcoin, and withdraw to a wallet you control.

b) You meet someone randomly on the street, and buy 1 bitcoin from them.

Now, the question is about how your personally identifying information can be linked to your future Bitcoin transactions. In both cases above, lets assume that you now own one UTXO for 1 bitcoin. In both cases, the counterparty to your trade (the exchange/person) will know that you are the owner of this UTXO. The exchange will know much more about you (perhaps your full name, address, bank info, etc), whereas the random person will just know you as... well... a random person. 

Next, lets say you want to buy a bucket of rocks using your newly acquired bitcoin. The price is 0.25 bitcoin (they are very nice rocks!), so you send a transaction that spends your 1 bitcoin UTXO, and creates a 0.25 bitcoin UTXO (paid to the rock seller), as well as a 0.75 bitcoin UTXO (paid back to yourself as change). 

So what will the exchange or the random person be able to say about this transaction? The answer is: they will not know whether you now own the 0.75 btc UTXO, the 0.25 btc UTXO, or both, or maybe even neither! The rock seller will know the reality of the transaction, as will you, but third parties will not be able to know with absolute certainty. 

Tracking individual coins through time isn't technically possible, but there are some heuristics that can be used to make a best guess of ownership over time. Ultimately, Bitcoins are fungible, so with best practices a user can keep themselves relatively anonymous. Conversely, if a user only uses a KYD'd exchange's custodial wallet and sends/receives all transactions from that wallet, then they will have basically zero financial privacy against that company (and anyone that has access to that company's records). 

For more information on Bitcoin privacy, see this wiki article or this stack exchange post (it is an old post, so the wiki is probably more up to date, but the answers there seem largely applicable still to this day).