Store and forward delay

Imagine you want to mail a letter to your friend who lives far away. You put your letter in an envelope, write the address on the front, and then put a stamp on it. You put the letter into your mailbox and wait for the mail carrier to come and pick it up.

The mail carrier comes and takes your letter, but they don't just deliver it directly to your friend's mailbox. They take it to a big post office first, where it gets sorted and put onto a truck or a plane to go to a different city. This step is called "store and forward".

Once your letter gets to the post office in your friend's city, it gets sorted again and then finally delivered to your friend's mailbox. All of these steps, from your mailbox to the post office to the delivery to your friend, take time. This time is called "store and forward delay".

In computer networks, data packets are like letters that get sent from one computer to another. The process of sorting and sending these packets through different routers and switches, similar to how the post office sorts and delivers mail, is called "store and forward". And just like with mail, there can be a delay in how long it takes for the data packets to reach their destination because they have to go through multiple steps of store and forward. This delay is called "store and forward delay".