When people want to find a product or service on the Internet chances are they will use a search engine to produce a list of suitable web sites.
Because the Internet contains billions of web pages the list of suggested sites produced by each search engine can be huge. Getting your site to the top of those lists should be one of your priorities as it will dramatically increase the number of visitors to your site.
Unfortunately getting a high listing for your product or service is a very difficult and time consuming thing to achieve and maintain, involving optimising your site and repeated search engine submission.
Each search engine is only as good as the results that it produces they are very careful to ensure that they are not misled by inaccurate or deliberately misleading submissions by web site owners or unethical search engine consultants. Attempts to mislead a search engine (or mistakes that look like attempts to mislead a search engine) can lead to permanent blacklisting of your domain name.