.htaccess is the most common name for the per-directory server settings file for the Apache server. WordPress uses it to store the mod_rewrite configuration so it can handle "Pretty Permalinks". Use this tag only if you have problems with the file itself. [url-rewriting] should be used for the WordPress rewrite system in general, [mod-rewrite] when you talk specifically about the Apache module.

The most common name of the per-directory settings file for the Apache server. WordPress stores the mod_rewrite configuration for "Pretty Permalinks" here. [url-rewriting] should be used for the WordPress rewrite system in general, [mod-rewrite] when you talk specifically about the Apache module.