The former is the charged date while the latter is the booked date. Now, let us assume that Joe failed to make the payment on time. Also, the item's price might have changed between these dates. Hence, both the dates are required. Transaction Entries help keep a record of changes to an account.
Transactions help further by linking a withdrawal from one account to a deposit in another.
The above figure implies that every transaction is associated with two entries. This may not be the case always. The person decides to deposit both the checks into his checking account. This situation can be represented clearly in multi-legged transactions or transactions with multiple entries. Summary Account It is often useful to group accounts together.