You may include a link to the home page of a web site, but do not make it appear that the contents are your own. This means that you should not link it within a frame so that the title bar and address bar still have your title and URL. You should refresh the entire window or open it in a new window. It is also good practice to indicate that the user is leaving your site.
You should not normally link to a page other than the home page without checking the page itself and the site home page, and following links such as 'Copyright', 'About this site', 'Legal', 'Info' or 'Help'. If there is nothing which asks you not to 'deep link' (link other than to the home page), it is probably all right to do so. If a site owner asks you to notify them when making a link, you should do so. If a site owner asks you to remove a link, you should usually do so.