You may not want certain pages of your site crawled because they might not be useful to users if found in a search engine's search results. If you do want to prevent search engines from crawling your pages, Google Search Console has a friendly robots.txt generator to help you create this file. Note that if your site uses subdomains and you wish to have certain pages not crawled on a particular subdomain, you'll have to create a separate robots.txt file for that subdomain. For more information on robots.txt, we suggest this Webmaster Help Center guide on using robots.txt files13.
Brand new keywords sound super tricky to find — except for a ton of easy ones that come around every January: simply adding the year to whatever keyword you’re targeting. People can start getting traffic from “2020” keywords long before they show up with any kind of search volume in typical keyword-research tools, since their data lags. (Hat tip to Glen Allsopp, who I got that idea from.)
Consider the length of your typical customer buying cycle. If your products and services have a short customer buying cycle, meaning your customers know what they want, search for it, and buy it, you may benefit from SEM ads that put your product right where customers will see it. Longer buying cycles, where customers research and compare for weeks or months, may not perform as well with SEM, as there isn’t an immediate buy after seeing one ad.
Webmasters and content providers began optimizing websites for search engines in the mid-1990s, as the first search engines were cataloging the early Web. Initially, all webmasters only needed to submit the address of a page, or URL, to the various engines which would send a "spider" to "crawl" that page, extract links to other pages from it, and return information found on the page to be indexed. The process involves a search engine spider downloading a page and storing it on the search engine's own server. A second program, known as an indexer, extracts information about the page, such as the words it contains, where they are located, and any weight for specific words, as well as all links the page contains. All of this information is then placed into a scheduler for crawling at a later date.