Gmail is a free, search-based webmail service that includes 1,000 megabytes (1 gigabyte) of storage. The backbone of Gmail is a powerful Google search engine that quickly recalls any message an account owner has ever sent or received. That means there’s no need to file messages in order to find them again.
When Gmail displays an email, it automatically shows all the replies to that email as well, so users can view a message in the context of a conversation. There are no pop-ups or banner ads in Gmail, which places relevant text ads and links to related web pages adjacent to email messages.