When do we need to use 'SetDatabaseDefaults()'?

The first thing I want to sorry because maybe my question is too silly. But I'm only at beginner-level. I read some examples in Autocad.net development documents (in C#) and found that sometimes using SetDatabaseDefaults() on object. I read information in help but didn't understand clearly. Anybody can help me to explain when I need to use it. And use it for what?

Thank you so much

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