In blockchain terminology, a mempool is a waiting area for the transactions that haven't been added to a block and are still unconfirmed. This is how a Blockchain node deals with transactions that have not yet been included in a block.
Front-running is the “act of getting a transaction first in line in the execution queue, right before a known future transaction occurs.”
A mempool bot is a bot able to scan this waiting area, so as to be able to buy a token as soon as liquidity is added --> in the same block
A front-run bot is a mempool bot, but configure to "sandwich" your transaction. When it detects your transaction in the mempool :
It buys a lot of tokens right before you, to make the price rise
YOU buy at a very high price
It sells this tokens he just bought, and make benefits
Can I use Sniper bot with default nodes
Short answer is : NO
If you want good results on Sniper Bot, you need to use a private node (or at least rent your own node on Quicknode).
RPC nodes often detect bots scanning mempool and block them
RPC nodes are slow and will not give you good results
Some RPC nodes do not allow you at all to scan mempool