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Bitcoin transaction confirmation time refers to the period between the initiation of a Bitcoin transaction and the sender verifying payment. This transaction time can be anywhere from a few minutes to several hours. A Bitcoin transaction without confirmation, zero confirmation transaction, means that the sender can still reverse it and probably double spend. The average confirmation time for a transaction with higher transaction fees is lower than the contrary. Traffic/congestion on Bitcoin’s network causes congestion in the mempool, which means that transactions have to take some time because of the sheer numbers competing with the rigid block addition time.