Keyword Frequency
Keyword frequency is a measure of the number of times keywords occur within a page's text. It's tied to the concept of keyword density. Search engines want to see more than one repetition of a keyword in your text to make sure it's not an isolated case. The recommended repetition is 3-7 times.

Keywords in page text

• Include at least 100 words in page text
• Use keywords at the beginning of the page
• Place keywords close to each other
• Repeat keywords 3-7 times for every 100 words

Keyword Prominence
The best place to place keywords in the text is at the top of each page, preferably the main page. The closer your keywords are to the start of the page or the start of a sentence, the better. This concept is known as "keyword prominence." You'll frequently see it used to describe search engines' algorithms.

How to choose your keywords
Choosing the right keywords is the first step to better search engine positioning. Analyze your business carefully and think of all the words that relate to your company or product.

As you think about keywords, consider the following:

Who needs your service?
Think about who will use your services, then target them with keywords. For example, people whose dogs are about to have puppies will need puppy food, so you can add phrases like "dog pregnancy" and "puppy health" to your list.

Include variations of your keywords
People will search for your site using all sorts of keywords. Making your site easy to find means including misspelled, capitalized and plural keywords. Always include the longer forms of keywords too. For example, use "domestication" as well as "domestic."

Avoid wrong keywords
Do not use "stop words" -- particles like "and" and "the" and common words like "Internet." Remember, the more specific your keywords are, the better the chance that people who find your site through search engines will actually benefit from its content.