Search Engine Optimization is the process of improving the visibility of a website on organic ("natural" or un-paid) search engine result pages (SERPs), by incorporating search engine friendly elements into a website. A successful search engine optimization campaign will have, as part of the...
Information graphics or infographics are graphic visual representations of information, data or knowledge intended to present information quickly and clearly. They can improve cognition by utilizing graphics to enhance the human visual system’s ability to see patterns and trends. Similar...
Nofollow links are those which do not pass any link juice. Its just a sign for search engines saying “Don’t Follow this link” or “Don’t count this”.
Benefit
1. Traffic, Traffic and Traffic
2. Makes your Site Look Natural
3. Increases DA, PA & other Metrics
4. Builds Authority
5. Safest tag
Affect google penalty : Google penalties can result in the drop of rankings for every page of a site, for a specific keyword, or for a specific page. Any drop in rankings brings with it a major drop in traffic for the site.
You can read more information in wikipedia