Explanation:

- Rights Issue: This involves offering new shares to existing shareholders in proportion to their current holdings at a discounted price. It's more of a method of raising capital from current investors rather than floating new shares to the public.

- Offer for Sale: This is where a company sells its securities en bloc to a broker or intermediary at an agreed price, who then resells these to the public. This method is used to distribute shares widely without the company directly handling the sale to the public.

- e-IPOs: These are electronic Initial Public Offerings, where shares are issued to the public through digital platforms and can be seen as a digital version of offer through prospectus. It's primarily an electronic mechanism for bringing out IPOs.

- Offer through Prospectus: In this method, the company invites the public to buy shares by publishing a prospectus detailing the share offer. This traditional method involves direct sale to the public.