Tip provided by Deb and rewritten by Miraz.

A good way to increase security on your site involves the .htaccess file. You can override server settings to allow or prevent directory listing.
Prevent directory browsing

Suppose you have a directory which doesn't have a default file (index.html), such as a folder of images, for example. A visitor may enter an address ending with a / and see a list of all the files in the directory.

You can prevent directory browsing by adding this line to your .htaccess file:

IndexIgnore */*
Allow directory browsing

There may be times when you want or need to allow visitors to browse a directory. For example, you may need to allow access to files in a directory for downloading purposes on a server that is configured to not allow it.

Many servers are configured so that visitors cannot browse directories. In that case visitors will not see the contents of the directory but will instead get an error message.

You can override the servers settings and allow directory browsing with this line:

Options +Indexes
Password protection

Tip provided by Sheila from the WW list and rewritten by Miraz.

You can password protect individual files with .htaccess. It's usually done directory-wide with <Directory> but you can use <Files> to specify a single file:

<Files secret_file.html>
    AuthType Basic
    AuthName "Team Page"
    AuthUserFile path_to_password_file
    Require user username
</Files>

This only protects the single page; all the files that it is linked to are not protected. More detailed information: httpd.apache.org/docs-2.0/howto/auth.html.
Block various bots

[Stephanie of Glenfinnan Web Hosting supplied this information which was rewritten and amplified by Miraz with reference to: www.webmasterworld.com/forum13/687.htm. Stephanie said: You can block various bots with the .htaccess file, Gini and someone else [from the WiseWomen list] posted their list of spam and spider bots [6 Kb txt file] awhile back.]

Spambots frequently visit our sites for various nefarious purposes. You can block them like this: