1. Exact phrase:

You are most probably to get better results when you put your search phrase in double quotes. Than Google will give you results with that exact phrase instead of synonyms. For an example if you type in: "marketing forum" Google will give you pages that contain those two words together.

2. Exclude word

When you put minus (-) in front of some word Google will give you search result excluding that word. For instance: ebook -free will give you pages that contain word ebook excluding word free.

3. Search for Keywords with Similar Meaning

Using sign ~ before some word will give you synonyms of that word. For instance if you type: shoes ~inexpensive Google will give you page results cheap shoes, affordable shoes...

4. Any word in phrase

Operator * tells Google to give you any word on that place in phrase. For example: If you type: music * online Google will give you results like music education online, music radio online, music streaming online...

5. File type search:

If you are using for specific file type like PDF just type filetype:pdf after your query. For instance: "how to paint"  filetype:pdf will give you PDF documents with query how to paint.
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very informative post.great tips,thanks for sharing with us.

Thanks a lot to you for the detailed suggestion, It will definitely help me a lot for doing SEO of a site.

Really these are the good tips to search as we with! thanks to share this.

really great post. know about it but described it detailed.

Thanks for the tips, it was really helpful to me!

Google will include all the terms specified in the search.  If you are looking for any one of one or more terms to match, then you can use the OR operator.

Exact word is important to get the exact meaning or description of the words.

Thanks for sharing very much useful information. Before I haven't known that Google search is providing sign searching facility. I am interested to know more. Can you please share other Google Search methods here?

use advance tools in google search it is available as search tools where you enter your keyword in the search engine.