Depending on your needs and budget, one solution may be advertising in magazines, newspapers, TV, radio or other traditional media. But lets assume you're going to advertise on the Web instead.
Here's a few types of online advertising:
- Paid positioning in search engine results
- Contextual paid advertising
- Banner advertising
- Cajoling other web masters to linking to your site
- Email contact properly conducted (not SPAM)
- SPAM (unsolicited email)
Paid positioning
Many search engines follow a "pay per click" model. You make a deal with the web site where you bid based on keywords and desired placement in the results, and your cost is based on how many "clicks" you recieve. That is, every time someone clicks on the link you put in the search engine, you pay for that click.
Payperclicksearchengines.com offers extensive information on this sort of promotion.
Contextual paid advertising is a variant where the service tries to match the topic of your advertisement with the topic of the page it will appear on. Google's AdSense/AdWords program is a fine example of this, but Yahoo offers a similar service.
In the AdWords system you write a 3-line advertisement, assign keywords to it, and assign a maximum cost per click you are willing to pay. Google takes those maximum cost-per-click on each keyword and runs it like an auction, with the placement of the advertisements being a combination of the amount the advertiser paid and the closeness with which the keywords match. You don't pay for placement of the advertisement, but when someone clicks on it. However they scootch you towards better and better ads by charging more the lower your clickthrough rate, and sometimes outright banning you for a low clickthrough rate.
Banner advertisements
Banner advertisements are handled differently than pay-per-click or a program like Google's AdWords. I've never used these programs so only know the details from a distance. The programs generally involve large "buys" (tens of thousands of dollars per month) and you're paying for placing the advertisements.
The banner is a graphical rectangle that can be square, horizontal or vertical. They come in some standard sizes such as 460x60 pixels. The banner can be animated.
Publishers sometimes don't like banners. One of the advantages of the AdSense style advertising is you can control the color and styling of the advertisement, and therefore control how well it blends with the design of your web site. With the typical banner advertisement the website publisher cannot control the look of the banner, and often it will be highly clashing to the website design. Neither can they control with any great precision the topic of the banner.
Email and SPAM
Not all email advertising is SPAM. It is possible to do properly conducted email advertising that is not SPAM.
What is SPAM? It's unsolicited advertisement through email. That is, advertising which you never agreed to receive. In other words, the electronic equivalent to the junk mail that clogs up our physical world mailboxes at home.
When is email advertising okay? Well, it is when the recipient has AGREED to receive email advertisement. The common way to get agreement is through signup pages on web sites. It is good form to email a verification request, and only place that email address on the contact list when they respond to verify that they do indeed wish to be contacted.
Many of the marketing tips and strategies offered by Internet Marketing Experts seem to be SPAM mongering strategies. If you want to do this (email based marketing) in a legitimate fashion, then make sure to take all the steps to ensure the people know they are going to receive email advertisements from you.
In any case, email advertising is simple. Make an email message, and then send it out. Used well this can be very effective. But it's easy to wander into the territory of being a SPAMMER, which will (apparently) earn you lots of negative karma. SPAM is highly intrusive and is, in my opinion, a blight on the Internet. SPAM could well cause a mass exodus away from the Internet.
Business calculations
Each time your "advertisement" is shown, this counts as an "impression". The "click through rate" (CTR) is a simple percentage calculated as so:
CTR = number of clicks / number of impressions
Presumably your business model is to sell goods or services through your web site. In that case it works out like so:
Advertising cost = number of clicks X cost per click
Conversion rate = number of sales / number of visitors
Profit or loss = Sales income - Advertising cost - web site costs
In other words, the business end of this is to keep sales income ahead of the other costs. The other calculations help you gauge how effective your various efforts are.
For example, the CTR measurement shows how effective (or ineffective) your advertisements are. The conversion rate shows how effective (or ineffective) your web site is in getting the visitor to buy.