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When I look at blockchain.info or blockexplorer.com, it shows the latest blocks.
The most recent block, #283653, has time 2014-02-01 22:42:08. The previous block, #283652, has time 2014-02-01 22:45:57.
So the previous block has a timestamp larger than the most recent block. How is this possible?
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Block timestamps are not very accurate and are allowed to be up to several hours off. It is difficult for a decentralized network to come to an agreement on an official time.
Reasons that it might be inaccurate are different system times, lag, and also miners often change the time by small amounts once they have tried all possible nonces. This allows them to get new hashes using the old nonces.
