What is the difference between Indexing and Crawling?

When the Search Engines come on your website and read the webpage content, this process is called crawling. Whereas whenever search Engines come on your website, which ever page they crawl, they take a copy of that page with them and save it on their server. This process done by the search engine is called Indexing.

Thanks for making me clear on this issue.I was little bit of confused with their indexing process.

Yes dear indexing means a carbon copy save by the search engine to its database. But crawling means read the content bye the Search engine of web page.

Crawling means collecting the data,and indexing means giving a unique id to every URL.

Crawling is the process of reading the data on the page, indexing is putting this data (and other meta data) in the search engines database (index).

Crawling:: Crawling is the process of an engine requesting -- and successfully downloading -- a unique URL. Obstacles to crawling include no links to a URL, server downtime, robots exclusion, or using links (such as some JavaScript links) from which bots cannot find a valid URL.

Indexing::ndexing is the result of successful crawling. I consider a URL to be indexed (by Google) when an info: or cache: query produces a result, signifying the URL's presence in the Google index.