Like life itself, there is only one constant in link building: change.
Many tactics that worked in prior years no longer do since Google caught wind of them and reconfigured its algorithm to make those tactics a liability rather than an asset.
The key for any link builder or webmaster is to stay one step ahead of any such changes. By focusing on natural content geared toward the end user, you can usually stay in the clear. After all, there’s always a reason that the strategy at hand stopped working.