Absolute beginners on the Internet often find email addresses about as understandable as ancient hieroglyphics. This week we explain how to make sense of them...

Q: What do all those squiggles mean?

A: Take an example of someone called John Smith, who has an email account with Oceanfree.net. The name he chose was "johnsmith", so his email address is:

"johnsmith@oceanfree.net"

Q: But it still looks like a whole load of squiggles...

A: Not really, once you get used to how email addresses are structured. The first confusion is that it's both your "name" in cyberspace, and your "address" too.

Q: What exactly is the @ squiggle?

A: That's commonly referred to as the "at" sign. In an email address, think of it as a dividing line between the person's name and the rest of the address. It separates the individual user or account ("johnsmith") from the rest of the address - from the name of the computer that holds the person's waiting email ("oceanfree.net").

So when John is giving his email address (johnsmith@oceanfree.net) to somebody over the telephone, he'd say: "johnsmith (all one word) AT oceanfree DOT net". The three components are:

* johnsmith (the user)
* @oceanfree (their organisation or Internet service provider)
* .net (the bit that indicates the type of organisation, or sometimes refers to a country code).

Q: So the address has different "levels"?

Right. Think of those squiggles as the name, address, postcodes etc on a sort of electronic envelope. This information always goes in the following order:

* the username;
* the @ (or "at") sign;
* the name of the organisation - a private company, university etc, or an Internet service provider such as Oceanfree;
* the "top level" of the domain they are coming from - a country or a type of organisation.

Like the Internet itself, an email address is organised in various tiers. For example, you might receive a message from somebody in an Irish company, and their email address is in the format username@companyname.ie

In this case the final .ie (or "dot ie") part of the address indicates the highest tier - what country they're coming from. The top-level Internet domain name for Ireland is .ie, for Britain it's .uk, Germany is .de (or Deutschland) and so on. The one main exception is the US.

Q: Why?

A: It's basically an accident of history. The Internet began in the United States, so they never got around to this foreign names convention. For example, Microsoft's Bill Gates handles email questions at his address "askbill@microsoft.com". The "com" stands for "company". A two- or three-letter convention evolved, so that the email address could show what kind of organisation you're in.

And just to make things slightly more confusing, there are two variants of this convention - the US and non-US one. So "com" (or, on this side of the Atlantic, "co") is a private company, "edu" (or "ed") is an educational establishment, "gov" a government body, and "org" a non-governmental organisation. "net" is a network infrastructure or networking type organisation, such as Oceanfree.net

Q: I notice that sometimes when I get email from people in companies in Ireland, they don't always have "co" or "com" in their address. Why's that?

A: Because this two- or three-letter organisation tag is optional in countries such as Ireland.

Q: How do I get somebody's email address in the first place? Does the Internet have anything like a telephone directory?

A: The simple answer is: no. The Internet is so big and decentralised nowadays that there is no one single catalogue of its total resources. Some "yellow pages" type email directories do exist, but they tend to be patchy because they depend on users registering their email addresses with them. The biggest Irish email directory is Esearch, at http://www.esearch.ie

Q: Ask a silly question - how can you send someone email if you don't know their email address?

A: Either find it out by telephoning them, or guess it. For example, supposing you want to send an email message to Jane Smith at Acme Chemicals...

Step one is to find out the company's domain name - what goes after the "@" sign. When its email addresses are given on its Web site or in its printed literature, you spot that they all seem to have "acme-chemicals.ie" after the "@" sign.

Step two is to work out what goes before the "@" sign. Try to spot the organisation's email naming convention for its user accounts. It might allow its users to put their surname first, or it might have decided to use underscores or hyphens. For example, here are six different naming conventions:

janesmith@acme-chemicals.ie
jane@acme-chemicals.ie
jsmith@acme-chemicals.ie
smithj@acme-chemicals.ie
j_smith@acme-chemicals.ie
smith-j@acme-chemicals.ie

In each case, the account name is determined by a different convention, but the domain name (the bit after the "@" sign) remains the same.

Step three: have a go. If you reckon the naming convention is along the lines of smithj@acme-chemicals.ie (as opposed to jsmith@acme.ie), try sending an email message to that address. The very worse that can happen is that you've got the person's account name wrong (the "jsmith" or "smithj" bit), and the mail "bounces". This means it's automatically sent back to you within an hour or two of sending it, with the electronic equivalent of a "return to sender" sticker on it. At least this means you can be certain that the mail hasn't arrived, so by process of elimination you can narrow it down to the right account name.

Another trick is to send a message to "postmaster@acme-chemicals.ie" asking for Jane's address - the Postmaster looking after Acme's email system might be able to help you out.

Q: Can you have a blank space in an email address?

A: No - there are no spaces in cyberpace! They aren't allowed within an Internet name or address, so people make do with hyphens to make the name easier to understand (eg acme-chemicals.ie). Apostrophes aren't allowed either (so if your name is O'Brien you'd have to shorten it to "obrien").

A valid domain name and email address has to be based on a combination of characters of the Roman alphabet, and numerals, hyphens or underscores. But never blank spaces. And don't forget any dots or hyphens or squiggles in somebody's address - the system for sending email around the world is fussy.

In Oceanfree.net's case, you can choose any of these naming conventions when you set up your account (for example, the initial of your first name followed by your last name, or your first and last name both spelt out in full) - as long as (a) you use valid characters and (b) somebody hasn't registered the name already (account names are given out on a first-come first-served basis).

Q: I've seen some email addresses which are a big jumble of numbers. What do they mean?

A: That might indicate that they're in a large "semi-enclosed" zone of the Internet such as CIX or the Microsoft Network. Some of these companies - such as CompuServe - used to give their users fairly impersonal numbers instead of names, so your address might be something horrible and forgettable like 74774.1361@compuserve.com. With oceanfree.net you can choose a much more easy-to-understand account name.

Q: But one thing is still worrying me. Where exactly IS my email address?

A: Strictly speaking, it's not pinned down to any particular place. It's a storage place, somewhere on the Internet - a larger computer than the PC you might be actually logging on with. In the case of Oceanfree.net, it's the machine at Ocean (the "mail server") which handles your incoming and outgoing mail. You could be reading the mail from a PC in your office, or at home, or, theoretically, anywhere else in the world. But the one email account on this central computer is the "actual" source of your outgoing mail to the rest of the Internet, and the destination of incoming mail addressed to you. Have we lost you yet?