When Does Google Display Alternative Titles and Descriptions?

When we type a search query there are chances that most of the times we see alternative titles and descriptions. Those titles and descriptions are expected by search algorithms based on search queries.  Depending upon the analysis of location of the query terms alternative snippets are generated by document retrieval systems.

The Way How Google Does Identify Rich Snippets

Following are some of the factors based on which Google classifies a best snippet:

1st Factor:

1.In reference to a search query paragraphs are recognized and a snippet is generated by calculating distances of recognized paragraphs.
2.A paragraph is identified by analyzing score and relying on length, distances of paragraphs.
3.As soon as a paragraph is chosen immediately snippet is generated which comprises of a large number of predetermined characters of preferred paragraph.

2nd Factor:

While 2nd factor is that depending on search query a paragraph is chosen and snippet is generated by counting location of query terms with in document.

How does Google decide upon snippets for search results when it chooses snippets from the content of pages?

Google displays meta description as a snippet at times only if it is well written with keywords included in it that are required for that page and has around 150 characters. Even there are chances that google sometimes displays a sentence that is well written from the content of a page.

Even though there are no words or phrases in meta description for the page which is optimized but if that page ranks well in search results then its meta description appears as a snippet. There are cases such as a page may not even have meta descriptions, or a page might have meta-description that is identical to every other meta description, or even a page might have very short meta description and is not at all descriptive.

Here are some clues that from where does Google displays content and when does it chooses to display content from a page:
1.If in case search terms appear on pages which have lengthy introductions or abstract then Google make a decision to draw content from start of a page to display it in search results.
2.If in case search phrases of ranking pages appear in conclusion of a page then Google displays content from conclusion of page as snippet.

Numerous Snippet Generation Algorithms:

Google depending on perception of search query may decide to use which algorithm to generate a snippet for that particular page. There are chances that Google looks at length of paragraphs that comprise query terms and distance of paragraphs either from start of page or end of page. Some documents such as scholarly literature may have a high metadata where as a blog or ecommerce page might have less meta data.

Location based rules and language based rules are the two ways by which Google decides a snippet.

Location based rules:

Location based rules are those where a snippet is chosen by relying on location of search queries in a page or a paragraph is selected either from beginning or end of a page. Each paragraph is ranked based on length and distance of paragraph either from one location that is start or end where search queries are present.

Beginnings of pages are chosen for snippets if page comprises of abstracts, executive summaries or comprehensive introductions. While to select a snippet from end of page it should either contain a conclusion or else summarization of that document.

Language dependent rules:

To select a snippet these are some of language dependent rules:

1.Percentage of punctuation characters in a paragraph.
2.A punctuation or preposition is used to end a paragraph.
3.Are words in paragraph lengthy?
4.How many bold or italicized words present in a paragraph.

 Even though a paragraph contains all search phrases there are chances that it may not be selected as snippet due to following reasons:

1.If a paragraph is very short.
2.In case if a paragraph is overly punctuated.
3.If a paragraph fails to maintain language specific rules.
4.If it has bold or italicized words above threshold.
5.Even if search query is too far from both ends of page.

A snippet is chosen if it scores above threshold for that particular page. And also if it maintain below rules:

1.Selected paragraph should contain predetermined number of words.
2.It should contain first 2 to 3 sentences of paragraph.
3.Either middle portion of page contains one of the search queries.
4.It can be either entire paragraph.

A snippet is important for a page as it determines users to click it from search results.