Relative Clauses: Defining vs. Non-Defining

Lesson 6: Relative Clauses (Defining vs. Non-Defining).

1. Overview
Distinguish between essential information clauses and extra commentary clauses using commas and relative pronouns.

2. Defining Relative Clauses
Provide essential information needed to identify the noun (no commas used):
- The developer who built this platform lives in Morocco.

3. Non-Defining Relative Clauses
Provide extra, non-essential information about a noun (always enclosed in commas; note that "that" cannot be used here):
- Nador, which is a coastal city, has beautiful weather.
- My mentor, who taught me database engineering, is an expert.

4. Practice Exercise
Add commas where necessary to make the sentence non-defining, or leave it as defining:
1. Python which is widely used in AI is a powerful language.
2. The computer that I bought yesterday is very fast.