Whenever you call it the birthday, the storm of how this form of communication took the lead was amazing. Today most of the business world  relies on email corresponding in one form or another.
Amazingly, the private communication is also very much influenced by it. While lately, with the rise of mobile, instant messaging is getting a huge push, it's not there to replace email. Email is still undisputed king of the communication. Here is why:
- Email is compatible. No matter what system, os, mobile, tablet, computer or other devices, almost all of them are able to send and receive email. Web-based (like Gmail or Yahoo mail) or on your device directly (Apple Mail, Outlook, KMail, Evolution)
- Email is present. Everyone has an email-address. No other medium, except the telephone, is more widely spread. No matter if in business or private, you can reach someone via email.
- Email is versatile. No matter what you want to sent, you can do it via mail. Many people use it to send photos, or links to photos or files. You can sent plan text or beautiful arranged HTML-Mails with inline images and links. Like a webpage. You can send greeting cards or embed videos. Try it, you can send your business correspondence or your love letter via email (did you ever try to combine these two? :) ). Richard M. Stallman uses email even for reading websites . The website will be captured and sent to his mail account for improved security.
- Email is fast. Normally it's blazing fast. With push-mail on the phone, there is no problem to even chat with someone. Sometimes I do that. The messages comes in near real-time.
- Email is secure (if you want it to be). You may wonder about this. But yes, you can secure an email with PGP/GPG. The metadata are still a problem. The possibility to get anonymous mail accounts helps for that.
- Blogging via email. Blogger.com e.g. let you set-up a secret mail-address where you can send blog articles directly to your blog being published instantly. Very nice. You can blog from virtually anywhere.
- Store files in the cloud with email. Amazon e.g. let you send files for your kindle device via emails and even converts them if needed.
- Take quick notes with email. Who is preventing you from sending a mail to yourself? No one. Set Up a Filter in you mail program or webmail. Make a folder and redirect any mail with the subject "note to self" or something like that, into it. Now you can take a note from anywhere by just sending it to your account with the subject "note to self".
- Store a website in your email account. For saving a page HTML (no images, text and links only) you can use
wget URLwith GNU+Linux or just save "WebPage only" from your browser. That saves an index.html that can be sent via mail inline or as an attachment. If you want the whole site, you could Print to PDF and attach the pdf-file to the email.There is your personal site archive.
Email is King.
 Book: Rebel Code: Linux and the Open Source Revolution