Index - Google stores all web pages that it knows about in its index. The index entry for each page describes the content and location (URL) of that page. To index is when Google fetches a page, reads it, and adds it to the index: Google indexed several pages on my site today.
Crawl - The process of looking for new or updated web pages. Google discovers URLs by following links, by reading sitemaps, and by many other means. Google crawls the web, looking for new pages, then indexes them (when appropriate).
Crawler - Automated software that crawls (fetches) pages from the web and indexes them.
Googlebot - The generic name of Google's crawler. Googlebot crawls the web constantly.
SEO - Search engine optimization: the process of making your site better for search engines. Also the job title of a person who does this for a living: We just hired a new SEO to improve our presence on the web.
Can Google Find Your Content?
Determine whether your site is in Google's index - Do a site: search for your site's home URL. If you see results, you're in the index. For example, a search for "site:wikipedia.org" returns these results2.
If your site isn't in Google - Although Google crawls billions of pages, it's inevitable that some sites will be missed. When our crawlers miss a site, it's frequently for one of the following reasons:
The site isn't well connected from other sites on the web
You've just launched a new site and Google hasn't had time to crawl it yet
The design of the site makes it difficult for Google to crawl its content effectively
Google received an error when trying to crawl your site
Your policy blocks Google from crawling the site
How to your content on Google?
Inclusion in Google's search results is free and easy; you don't even need to submit your site to Google. Google is a fully automated search engine that uses web crawlers to explore the web constantly, looking for sites to add to our index. In fact, the vast majority of sites listed in our results aren't manually submitted for inclusion, but found and added automatically when we crawl the web. Learn how Google discovers, crawls, and serves web pages.3
We offer webmaster guidelines4 for building a Google-friendly website. While there's no guarantee that our crawlers will find a particular site, following these guidelines should help make your site appear in our search results.
Google Search Console provides tools to help you submit your content to Google and monitor how you're doing in Google Search. If you want, Search Console can even send you alerts on critical issues that Google encounters with your site. Sign up for Search Console5.
Here are a few basic questions to ask yourself about your website when you get started.
Is my website showing up on Google?
Do I serve high-quality content to users?
Is my local business showing up on Google?
Is my content fast and easy to access on all devices?
Is my website secure?
You can find additional getting started information on http://g.co/webmasters6