Database index pros and cons

I just got a question from an interview about the pros and cons of database indexes. I instantly realized that I didn't answer it well even though it is very crucial knowledge (even for a front-end engineer like me).

Pros

• Better performance in searching or related tasks.

Cons

• Increased disk space.
• Slower data modification, and updating records.

Ref

• Advantages and Disadvantages of Indexing in SQL