Is a Web tagline a branding statement, an advertising slogan or a description of what your site offers?

I vote for #3.

If it's clever, it can enhance your brand and add personality to your site. If it's clear, it tells a visitor where she has landed and what your site can do for her.

Clear is more important than clever

A Web tagline is a tiny but key piece of site usability. A good tag captures a visitor's attention and interest long enough for her to decide if she is in the right place. This makes it a first step in the sales process.

An ineffective tag leaves your visitor guessing what you do. It makes work for him or her--not a good way to introduce how your product or service solves a problem.

Note: Your tagline is the short phrase that appears at the top of every page of your site, usually next to the name of your company and often embedded in a graphic that is part of the page template.

I asked usability guru Jakob Nielsen to comment on the tension between "clear" and "clever" in crafting a good tagline. Here's how he responded:

"The key job of the tagline for a website is to set the stage for enabling the user to interpret the choices and content that's offered on the site. In the usability lingo, the tagline should help establish the user's conceptual model. If the tagline is not clear, it may give people the wrong model and thus cause them to make errors or simply abandon the site altogether."

Your value proposition in 12 words or less

Translation: the purpose of a tagline is to quickly and accurately orient a new visitor to the purpose of your site. It answers the question, "Am I in the right place?" It's your value proposition in 12 words or less.

A clear, concise, jargon-free description works best. That said, "simple" is not easy to create.

If you've ever tried to write or rewrite a tagline, you know the confluence of clear and catchy is hard to achieve. Here's a tagline I stumbled across recently on aeworkforce.com that does it:

"Where great careers in design and construction are built" 

The site continues by describing itself as "The career center exclusively for architects, engineers and construction professionals." Some might cringe at this tagline--too cute, you say. Others may like it.

Taglines are more art than science

That brings us to the second rule of taglines. As a WordBiz Report reader put it, "Taglines are more art than science."

It's a bit like pornography. You know (a successful) one when you see it. It makes absolutely clear what the site is about.

It's simple: B2B products & services are harder to explain

Nielsen also notes that it's more difficult to write a tag for a B2B site:

"Most B2B sites sell products or services that are much more complex and have less connection to everyday experience. Summarizing a website's purpose is thus much harder in B2B than in B2C. That's why they pay copywriters the big bucks, or so you would think. On closer examination, it seems that most sites pay their copywriters to obscure the site's purpose rather than state it clearly."

B2C Example (It Works)

"Top Quality Elk Antler Nutritional Supplements," from alpinevelvet.com

Can you guess? The site is a B2C storefront and information site for this specific nutritional supplement (for both humans and pets).

B2b Example (it Doesn't)

"Time. With Integrity," from trusted-time.com

Stumped? This nifty-looking site, filled with useful content, offers sophisticated time stamping and synchronization applications. The tag, nice as it sounds, is vague and non-specific. It doesn't tell you what the company does.

Checklist to write, revise or evaluate your Web tagline

How do you go about writing an effective Web tagline? Or evaluating the one you are using?

• Brainstorm a long list; don't throw anything out
• Initially, don't worry how many words it takes
• If your tagline contains a keyword for your site, so much the better (however, as it's usually embedded in a graphic, the search engines will only see your alt tag)
• Ask yourself if you're absolutely clear about the market niche you are serving
• Will your target audience (a.k.a. ideal visitor) immediately understand your tag?
• If you have to choose, opt for clear vs. clever
• If you can't be clever, be absolutely clear
• It's OK not to be clever

Bottom line:

A good tag summarizes what your site is about. It quickly and clearly explains your product or service.