Keyword Density: Percentage of times a keyword appears relative to total words

Optimal Density: 1-3% for primary keywords, 0.5-1% for secondary keywords

Long-tail Keywords: 3+ word phrases that are more specific and less competitive

Stop Words: Common words (the, and, or, etc.) that are automatically filtered out

Frequency: Total number of times a keyword appears in the content

Keyword Stuffing: Avoid overusing keywords (>5% density) as it can harm SEO