Spaces, underscores or hyphens in file names?

Document names are best written with hyphens or underscores rather than with spaces. Otherwise, some browsers insert a %20 for the spaces, which is harder for search engines to read. Hyphens have been found to be the best, at least for Google.

Thus “Current widget price list 2010.pdf” becomes Current%20widget%20%price%20list%202010.pdf. The search engine sees “Current”, “20widget”, “20price”, “20list” and “202010”.  It’s much better  to name your file “Current-widget-price-list-2010.pdf”.