Is an abbreviated name made by using only the first letter of most important words in a longer name?

Yes, that is a common way to create an abbreviation, though there are other methods as well. This type of abbreviation is often called an initialism.

Here are some examples:

* USA (United States of America)

* FBI (Federal Bureau of Investigation)

* NATO (North Atlantic Treaty Organization)

However, it's important to note that not all abbreviations are initialisms. Sometimes, abbreviations are made by using the first few letters of a word, like:

* Dr. (Doctor)

* Mr. (Mister)

* Ms. (Miss or Mistress)

So, while initialisms are a type of abbreviation, they are not the only type.