For the most part that's the case. The rise of latent semantic indexing has changed that a little, but in most cases, you should use those terms verbatim to get the best results.
You should also use keywords more than once in order to instruct the search engines that the term is at the heart of your content's meaning and purpose, right?
In most cases, that's still a good idea. If you have a 2,000 word page and your keyword is only showing up once in the text, it's likely that the search engines won't key into its importance in terms of the overall message.
With those two observations behind us, we've set the stage for one of the most common blunders in the world of Internet content creation, site building and search engine optimization: keyword overkill.
You've seen it in action before. Someone has a site about “oblong widgets”.
They're page says, “Welcome to our site about oblong widgets. Oblong widgets are very popular. We sell a wide variety of oblong widgets to meet all of your oblong widgets. If you want oblong widgets, you've come to the right site. We're your oblong widgets headquarters!”
Strangely enough, you'll never find that site high in the rankings if you query “oblong widgets” (unless there is a real paucity of competition for the term).
Its keyword overkill and it doesn't work. In fact, it's a very bad idea. It's a good way to make sure you don't rank for your keywords, in fact.
First, even if it didn't upset the search engines, it certainly wouldn't make you any friends with your real human visitors. No one likes reading redundant text that seems to have a weird fixation with the repetition of specific terms. It's “junk” content and people will respond to it as such.
Second, the search engines don't like it. Search engines haven't mastered artificial intelligence yet, but they're well beyond the point of being fooled by constant repetition of a keyword. The biggest reason to avoid overkill? It doesn't work. Period.
So, what is the ideal keyword density?
There isn't one. How's that for tricky? You're probably safe if you're anywhere between 1% and 4%, but there's no real mathematical formula to determine optimal use. Anyone who tells you there is a magic number is deluding himself or herself.
The real trick is to combine natural use with other quality SEO maneuvers. Use the word the way you would if it wasn't one of your chosen keywords and then buttress its SEO value by placing it in an H1 or other appropriate tag. You might even try to bold or underline the keyword term for good measure.
The last thing you want to do, however, is to go crazy with a keyword.
Excessive use isn't fooling the search engines and it's frustrating to your visitors. Avoid overkill and you'll get much better results.
