Robots.txt

robots.txt is a file (with the “”.txt”” extension ) in the root directory of a web site, and it is used to restrict content and notify search engines crawlers which areas of your site are excluded for , which pages it may not index, and it can be a very useful and important file particularly for SEO. It can be used to exclude all your admin pages from indexing (for example, pages in the wp-admin section of WordPress blog), and also can be used it to prevent search engines from seeing duplicate content on your site.
Robots (that complies with the Robots Exclusion Standard) will read this file on each visit, so that pages or areas of sites can be made public or private at any time by changing the content of robots.txt before re-submitting to the search engines.

Additional Terms:

Rich Snippets
Ecommerce
Social Media
Yandex
Search Engine Reputation Management (SERM)/ Online reputation management (ORM)
Google Partner/Premier Google Partner
Responsive Website
Mobile-Friendly website
Google maps
Hashtag
Call To Action
Bounce Rate/Abandonment Rate
Mobile Marketing
Content Marketing 
Marketing Automation / Programmatic
Website Traffic/ Traffic Analysis
Geo Targeting
Quality Score
Lead Generation
A/B Testing
B2C Digital Marketing
B2B Digital Marketing
Doorway page
Dead/ Broken link
Wikipedia
Internal Link
Outbound Link
Inbound Link
Heading tags
Google Trends
Google Sitelinks
Google Keyword Planner
CTR (click-through rate)
CPC (Cost Paid per Click)
404 Not Found
Redirect 302
Redirect 301
200 OK Code
Alt attribute/ Alt tags
Nofollow link
Search engine algorithm
White hat search engine optimisation
Black hat search engine optimisation
White hat SEO
Google’s Penguin Update
WordPress
Usability
Organic Search Results
Link Building
Landing Page
Google Dance
Indexing
Email Lists
Duplicate Content
Domain
Canonical URL
Blog
Banners
Algorithm
Accessibility
Conversion Rate
Satellite Websites
Bid
Joomla
Google’s Knowledge Graph
Drupal
Link Exchange
Long tail
Google Webmaster Tools
Lead
Magento
Keywords
Mini Site
Search Engine
CMS
Site Map
Player Embed
Bread Crumbs
Google Panda Update
YouTube Channel
Contextual Advertising
Open Source
Google’s Search Engine Robot
Meta Tags
Affiliate Program
CPA - Cost Per Action
CPL - Cost Per Lead
Friendly URL
GDN – Google Display Network
Page Rank
Remarketing
ROI – Return on Investment
RSS (Really Simple Syndication)
SEM-Search Engine Marketing
XML–Extensible Markup Language