对于搜索引擎来说，页面各个元素的权重比例。

• Inbound link text: 10 points.
• title: 10 points.
• domain name: 7 points.
• large h1-h2 headings: 5 points.
• first sentence of first paragraph: 5 points.
• path or filename: 4 points.
• proximity (multi kws): 4 points.
• beginning of a sentence 1.5 points.
• bold or italic text: 1 point.
• usage in text: 1 point.
• title attribute: 1 point.
• alt tag: .5 point.
• meta descrip: .5 point.
• meta keywords: .05 point.