If you do a lot of research that involves a census or parish record, where the names and information is hand written by a enumerator or census taker.
Having a guide or an example of the handwriting that was common at the time, would be very helpful in being able to read and know what they were trying to record.
There are many helps out there.
I like to keep a sheet of paper with me when I do research that shows example of the way some letters or numbers might be written and what they are. You can also find many helps on the internet. One such place is britishgenealogy.com
You will find it here.