I'm learning about the mempool and found this text on a bitcoin educational site: Once the Mempool reaches full capacity, nodes start prioritizing transactions by setting up a minimal transaction fee threshold. Transactions with a fee-rate lower than the threshold are immediately removed from the Mempool.
If a transaction is removed from the mempool, where does it go? To some holding area, I assume, for possible inclusion in the next block? What is the name of the holding area and where does it reside? Thx.
Hosseinimr93 has pretty much said most of it. The fees on the bitcoin network as well as fee rate on the MEMPOOL is dynamic meaning it's not fixed it changes depending on average fees. The average closing fees on an already confirmed block would likely be the opening average fee for a new block. This simply means that if more bitcoin users decide to increase the fee rate they are making use of in their transactions just for them to get their transactions confirmed faster then the average fee rate on that block will increase also.
Nodes have a minimal fee rate known as purge fee. It's the smallest fee that would be ever considered by miners to be confirmed. Transactions with fees below the purge fee will be dropped automatically from the MEMPOOL and as fees go up the purge fee tends to increase also too.