Linkbaiting is the practice of crafting content that is designed to get other content producers to link to it. The purpose is increasing the number of inbound links to your content and thus improving its performance in search engine results.
The most important element of linkbaiting is creating compelling content, something that the reader finds value in. Examples of link bait, in this context, include breaking news, striking images, infographics, controversy, humor, educational material and applications. If your content has value for readers, they are likely to share the link.
Beyond the quality of the content itself, the most common linkbaiting tactics are creating titles that draw readers to the content and developing reciprocal relationships with other content producers, in which you share links to their content and they to yours.
Both linkbaiting tactics can be used either well or poorly. A well-crafted title grabs the reader's attention and accurately represents the content. However, one common misuse of linkbaiting is the creation of catchy -- but misleading -- titles for articles. Similarly, if you share links to high-quality content, you, your readers, and the content creator all benefit. However, if you frequently share links to content that is not intrinsically valuable, your own content will lose value for both readers and search engines.