The conversation view is a setting in Gmail that allows users to decide if they want emails with the same subject to be grouped. It's different from an inbox or primary section. Note that it's an optional feature, and you can turn it off. If your turn it off, your Inbox will display all emails separately as they come, instead of grouping them into conversations. Although some users still prefer this, it will put you at a disadvantage if you're someone that have lots of emails in a day. You might even end up searching for a message that you've already read and responded to.