Alberto knot (sometimes called the Crazy Alberto) was designed to join braided line to monofilament or fluorocarbon.
With the development of braided super lines in the ‘90s, anglers looking for a stealthier connection to lures and to build in a little shock protection because braid doesn’t stretch, began experimenting with knots that would allow them to attach monofilament or fluorocarbon top-shots or leaders to their braided mainline. The ideal knot needed to be easy to tie, have a small profile so it could travel through rod guides easily, and of course, be strong. The Alberto knot meets all these criteria.
While it is not as strong or slim as, say, the FG knot, it is much easier to tie (we’ve tied this knot in 10-foot seas), and it has proven itself to be strong enough. Although not quite as easy to tie as a Uni-to-Uni connection, it is smaller (thinner) and passes through the rod guides easier. We’ve been using the Alberto knot for years for everything from leaders for ice fishing for lake trout and Arctic char, to attaching leaders to tie on twitching jigs for salmon, to top-shots for downrigger fishing for Chinook, and we’ve never had it fail.
To tie it, double over four inches or so of the mono or fluorocarbon. Thread about eight inches of the braid through the end of the loop formed in the mono or fluorocarbon. Pinch both lines at end of the loop. Spiral the braid around both legs of the mono/fluorocarbon seven times, then pinch the braid and mono/fluorocarbon at the location of the last spiral. Then spiral the braid in the opposite direction seven times, crossing each of the initial spirals. Thread the tag end through the loop at the end of the mono/fluorocarbon in the same direction that it went in. Moisten the knot well, then grab the standing- and tag-end portions at both ends of the knot and pull very tight (this will take some force). Trim tag ends very close to the knot.
The Alberto knot has proven to be quite durable and long lasting. However, you should inspect it occasionally and if it’s beginning to look worn, cut it out and retie it. This applies to any braid to mono/fluoro connection, not just the Alberto knot.