Imagine you have a toy that you really love playing with. You want to share it with other kids but you also want to make sure they know how to use it properly and safely. To do this, you write down some important information about the toy that others should know, like how to assemble it, how to clean it, and how to play with it without hurting themselves.
A technical file is kind of like the instructions you wrote down for your toy. Only, it's not for toys, it's for other things in the grown-up world that people use every day, like phones, appliances, or medical devices.
The technical file has detailed information about how the item was made, what materials were used, and how to use it safely. Imagine that the phone you use every day has a technical file, it would tell us about how the phone was built, what parts it has, how it works, and what to do if something goes wrong.
The technical file is really important because it helps people make sure that items they use are safe, reliable and do what they are supposed to do. Just like how you made sure that your toy instructions made playing safe for other kids, technical files make sure that the things that grown-ups use are safe and work really well.