Is Demat account and DP Account the same or are they different?

My DP insists on nomination facility in my demat account. Is that compulsory?

What is the process to dematerialize my physical shares and is it safe to keep shares in DP account? I am worried after the Karvy case.

Are the terms and terminologies in commodity trading the same as equities and F&O or are they different?

Are there different types of saving accounts?

As a demat account holder with a leading bank in India, are there are any safety measures that I need to adopt to be on the safer side?

Can I directly apply for IPO shares in my demat account?

Can I hold my shares across 2 or 3 demat accounts?

Can I hold shares in BSDA account just like normal demat account?

Can I participate in securities lending and borrowing mechanism using my shares in the demat account. How will it work?

Can I use the same demat account for commodities also?