Email client

Your email client is the program you use to read and send emails with. For most people this means something like Outlook, Gmail, or Apple Mail.

In many cases you don't have just one email client. For example, if you're using Gmail as your email provider, you might use the default Mail app on your iPhone, Airmail on your Macbook at home, and when you check your personal email at work (hypothetically, noone ever does that, of course), you open gmail.com in your web browser.

Generally speaking email clients come in two flavors; the ones that are downloaded to your device or the ones that you access via a web browser.

In the above example, Mail app and Airmail are downloaded applications on your phone and laptop (even if one came preinstalled), while gmail.com is a browser-based application.