EclecticEnglish.Com

[pambele]

Can anyone explain the difference in layman's terms?

Thanks

[nikita]

Hello,

In simple words about the defining and non-defining classes.

If you remove a non-defining clause (a kind of a smaller sentence that is a part of a bigger sentence), some information will be definitely lost, but it will still remain a normal and meaningful English sentence. This is because the clause does not define anything; it just provides some more information.

If you remove a defining clause from a sentence, the meaning will inevitably be lost.

Here are a few examples from Headway. You can easily see whether a noun is already clearly defined or not. If it is clearly defined, then we will most likely have a non-defining relative clause after it. Otherwise, the noun should be followed by a defining relative clause.

[nikita]

Hello again

What you also need to remember is that non-defining clauses are separated by commas, while defining clauses are not.

And here is another very good example from Headway.

[pambele]

Thanks very much, Nikita. I kind of cracked it before I read your excellent posts, which just confirms things. Essentially, anything parenthetical requires commas and non-defining clauses are parenthetical remarks in a bigger clause.
Again, thank you.