Where are the decimal places?

Excuse me, but I'm a bit confused about the decimal places in cryptocurrency transactions. Could you please clarify where exactly these decimal places are located? Are they always present in every transaction, or are they only used in specific situations? And how do they affect the overall value of the transaction? I'm particularly interested in understanding how these decimal places work in terms of their impact on the precision and accuracy of transactions. Thank you in advance for your help.