All visa application guides are written by former UKVI staff, with extensive experience as immigration caseworkers, and subsequently, as professional immigration advisers registered with the Office of the Immigration Services Commissioner (OISC).
These guides break down the immigration rules into plain English requirements, and highlight the practical considerations for your application type.
But more uniquely, these guides and templates offer an insight into how applications are considered and assessed from the point of view of UKVI caseworkers.
These example letters, templates and guides are offered for free, for your personal immigration application.
They are intended as guides to structure and content for your own letters. You do not need to copy them word-for-word, necessarily.
It is also imperative that you adapt these letters according to your own personal circumstances.