I am not a lawyer, and I don't portray one on TV. But I've been around a long time....
Links from Site A to Site B are generally legal provided that they do not constitute fraud or libel. For example, Google links to zillions of web sites don't require the permission of the site owner. Google links are not fraudulent, since they do not pretend that Google owns the content. Google links are not libelous, since they do not associate the link with malicious commentary.
A link from your site to another should always make clear that you are referring to another site. Traditional links, where the user clicks, and gets a new web page with that site's address displayed, are reasonable.
Using links to include other site's content (GIFs, JPGs, etc.) in your web page is not clearly referring someone elsewhere; it is a pretense that you own the content, so you are committing fraud.
Publishing content like "This site <link> is run by a &^$#%*&" may be libelous, and may be subject to restriction in your country. It is certainly dis-courteous.
If the purpose of your link is to dramatically increase traffic to the other site, as a courtesy, you owe the other site a notification.
If the purpose of your link is to confuse your visitors, or to cause difficulty to the other site (such as suggesting that MoHPC is a "great" link from an Adult Erotica site), you are being dis-courteous, and perhaps fraudulent.
