Back in the good old days of jailbreaking, your first step before upgrading to the latest version of iOS was to plug your device into an app called TinyUmbrella and save your SHSH blobs.
What are blobs? Simply put, saving your blobs gave jailbreakers the possibility of downgrading their devices to a previous version of iOS. Unfortunately, with iOS 5, Apple caught up with the way jailbreakers were using blobs, making TinyUmbrella virtually useless.
Now that’s changed. Three years later, it finally appears that the blobby wind is blowing in the opposite direction, and a new TinyUmbrella beta has been released that once more allows jailbreakers to save their SHSH blobs.