No one really. Not during those times you’re just using your email. It mattered when you set up your email or set up your phone to get your emails. You may remember a question during that setup…POP3 or IMAP. But then it was gone, and so was your memory of it. You rarely need to think of it again.
But it does kind of matter. It changes where your emails are located. Where those actual little messages with their attachments are physically stored. It also affects what you can do with them…but that’s only true if you’re using an email client like Outlook or Thunderbird.
So, basically, IMAP stores the emails on your provider’s server. The provider can be Gmail, Yahoo, AOL, Outlook.com, or your company. Whether you’re using a web based email system (webmail using your browser) or a client email program like Outlook or Thunderbird, those emails never get downloaded to your computer…they stay on the provider’s server. This is the better option. It allows you to check your emails from different devices or different locations.
POP3 is an older method, and it actually downloads the messages to your device or computer, and then usually deletes from the server. IF you setup a POP3 email account on your phone or other device, you can tell it (your device) to NOT delete the email. People do this so that it can then still be downloaded to their computer at the office or home.
IMAP gives you access to all your folders, and allows you to create, delete, and edit folders. It allows you to move your emails around to the different folders.
POP3 only allows you to access your InBox, and only email messages in your Inbox, not folders.
Webmail Archive Manager allows you to archive or backup your emails using either IMAP or POP3…though, it’s far easier to use IMAP. Most providers will allow you IMAP access to your web based email account.