A Web-based service lets you send and receive email via any web browser. How they do this uses complex prgramming which is beyond my knowledge. It has varying reliability, and some won't handle attachments or other features. You will also most likely be splathered with ads. However, this means you don't need any special software, and you can access your own email from any web-connected computer.
Most services offer the latter.
This is effective if your regular email address is subject to change, like a school or work based address, but the forwarding address supposedly never change and always send to whatever address you are currently reading. Service from the popular web directory. Puts your real name in all messages. Puts your real name in all messages. Has spell check and filters.