Checksum is a technique used to detect errors in data transmission. It involves adding a series of numbers to a block of data in order to produce a single number, known as the checksum value. This value is then sent along with the data to the receiver, who can use it to check if any errors occurred during transmission.
An analogy to explain checksum is a person who needs to send a package to someone else. The person decides to add a small card with a list of items inside the package and asks the receiver to check the list and ensure that all items are present. However, the sender also decides to add a checksum value, which is the total weight of all the items in the package. When the receiver gets the package, they check the list and make sure all the items are present, but they also weigh the package and compare it to the checksum value. If the weight matches the checksum value, then the receiver knows that no items were lost during shipment.
In the digital world, checksum works similarly. A sender adds a checksum value to a block of data before transmitting it. The receiver then calculates the checksum value of the received data and compares it to the checksum value sent by the sender. If the two values match, then the data was transmitted without any errors. If they do not match, then the receiver knows that there was a problem with the data during transmission and can request it to be re-transmitted.
