What does it mean when a transaction is pending?

When you see a pending transaction on your credit card or bank account you may ask.
What does it mean when a transaction is pending?
When will it clear?
Pending means a transaction to withdraw money from your account or add money to your account has been submitted but isn’t complete.
The pending date may be referred to as a “transaction date”.
It is the start of a process that includes some back and forth operation between the place you made the purchase and your bank that manages the credit or debit account.
Once the transaction is cleared - pending transaction becomes posted.
The amount of a pending transaction may differ from the amount that’s posted to your account.
This is because merchants may pre-authorize an amount before the transaction’s complete.
Posted amounts can increase or decrease from pending.
For example, when you purchase gas, the station might pre-authorize your account for $100.
If so, you will only see a $100 pending transaction on your checking account or credit card.
But once your payment clears, the final amount posted will lower to how much money you actually spent on gas.
The same thing can happen if you add a tip at a restaurant; the pending transaction will usually show the pre-tip total, while the posted transaction will reflect the bill plus the tip you added.