When we want to send a letter or a package to someone, we need to write their address on it so that the postman knows where to deliver it. Sometimes people write the address in their own handwriting, which means they write it with a pen or a pencil.
However, not everyone's handwriting is the same. Some people write very neatly and clearly, while others write messily or in cursive (joined up writing). This can make it hard for the postman to understand what the address actually is.
So, when we talk about handwritten address interpretation, we are talking about the process of someone (usually a machine) looking at the address that has been written in someone's handwriting, and trying to work out what it says so that the letter or package can be delivered to the right place.
This is actually a really hard thing for a machine to do! Think about how different your own handwriting might look depending on whether you are using a pen or a pencil, or whether you are rushing to write something quickly or taking your time. Machines have to be very clever to be able to recognise all the different ways that people might write the same letters, and to be able to sort out messy, handwritten addresses from each other.
Sometimes machines are used to try and interpret handwritten addresses, but sometimes a real person will have to look at the address and try to work out what it says. This is why it's a good idea to try and write your address as neatly and clearly as possible, so that it's easier for the postman to read!