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.