Web based email is particularly useful, because it provides access to your email from any web browser.
Many web sites provide free web-based email access.
You typically access your email by logging onto a web based email program with a specified address and password. The advantage of these services is that they let you check your email from any web browser, anywhere, even while traveling around the world. The disadvantage of web based services is that they don't have as many features as full desktop email applications. For example, they sometimes restrict the size of attachments you can process. All you need to use these services from any web browser are your email address and password.