Guitarists are insatiable learners and the world is full of great guitar learning material. First of all, there are countless tablature books which show you in the easy-to-learn guitar tablature format how to play all your favorite songs even if you can't read sheet music. If you can read sheet music, then there is sheet music available for every popular artist and thousands of classical and lesser-known composers. There are also "method books" that teach how to play a particular style, and there are instructional guitar DVDs that show you and tell you everything a single guitarist knows how to do. There are books with CDs full of audio examples, there are DVDs that come with tablature books; the list of available guitar learning resources is endless.
Guitar lessons are still the number one way that guitarists pick up new information. In-person guitar lessons with a local guitar teacher are probably the most effective way to learn new things about the guitar. The world is full of part-time and full-time guitar teachers, who put their heart and soul into teaching their students how to be an ever-improving guitar learning machine. Guitar teachers are expensive, however, and not everyone has the money or the time to commit to in-person lessons. So while this is a truly effective method, it is not for everyone.
Over the last 5 years, online guitar lessons have become an outstanding resource for guitarists wanting to learn guitar at a convenient pace and at very low cost. In my opinion, online guitar lessons have come of age, and are now the best tool for learning guitar available to anyone anywhere. I don't propose that online guitar lessons should supplant books, sheet music, DVDs, and in-person guitar lessons. What I would like to suggest is that online guitar lessons are more convenient, cheaper, more useable, and provide more breadth of information than any other method available.
Convenience: Tablature books are OK, as long as they come with some audio examples. DVDs are OK, as long as they come with a book. The problem is that keeping your place in the book and your place on the CD/DVD in synch is difficult. Every time you take a break (every day basically) you lose your place and have to synch up all over again. Online guitar lessons, on the other hand, solve the problem of synching the tab, explanation, and audio/video samples. A web page is the ultimate guitar lesson format: audio, video, and text all together in one document.
Price: Books and DVDs have to be manufacturer, shipped, and inventoried. If you have ever burned a CD or made some copies at a copy shop, you know that manufacturing a product costs real money. Imagine if you had to turn around and sell your product at a profit? Shipping a book or DVD to the retailer is another expense in traditional publishing that occurs before the product is even ready to be sold. Inventory, the hidden expense, can be the largest: every month the book sits in the store, it costs the owner a percent of the price to pay for it to be kept out of the rain, and if the inventory is bought on credit, there is interest on the loan as well. All told, it is no wonder there are few places that sell guitar lesson products even in a large city.
Breadth: Guitar books generally can only have a few hundred pages; DVDs can only hold a couple of hours of video. A web site can expand to the size of a whole library full of books and DVDs. This is one aspect of the size advantage of online guitar lessons, but the more important aspect is this: getting a book published is so difficult, that many great guitarists simply never try it. Publishing a web site is so easy that many fantastic guitarists who would never previously have published their knowledge can now publish their guitar lessons online where you can find them.
As you can see, online guitar lessons have significant advantages that should make them an important part of any guitarist's learning strategy. As the internet continues to grow, and the use of video on the internet spreads, look for online guitar lessons to one day be the recognized leader in helping guitarists improve their skills in a convenient, inexpensive way.