Ok, let's get the story straight here. Dobro is a trademark name for a resonator guitars. Originally coined by the Dopyera brothers when they formed the Dobro Manufacturing Company, in time it came, in common language, to mean any resonator guitar, or specifically one with a single inverted resonator. In bluegrass,the slide guitar is often referred to as a Dobro, even though it is just a normal acoustic played in slide fashion.
The trademark is now owned by Gibson. When Gibson acquired the trademark in 1994, the company announced that it would defend its right to Dobro's exclusive use. When Gibson informed other dobro guitar makers of its intention to reserve exclusive rights to the Dobro name, some players began to refer to their instruments as TIFKAD guitars, meaning "The Instrument Formerly Known As Dobro".
A true dobro can either be tuned and played like a normal acoustic guitar, or as it is more commonly played with a slide. The slide players that hold the Dobro like a normal guitar play in either a standard or open tuning. Most that play it on their lap, or in a like position standing with a strap almost always play in one of the open tunings. There are 2 types of dobros: squareneck and roundneck. Roundnecks are typically played in Blues music. Squarenecks, preferred by Bluegrass players, have strings that measure 1 cm off the fret board, and are played on their backs with the strings facing up. In contrast, roundnecks are usually held like a guitar.
There are many tunings used for Dobro. Standard, Drop D and Open G are probably the most commonly used tunings. However many other tunings are used and easily found by entering "Dobro Tuning" into Google, or your preferred search engine.
If you don't have a Dobro yet you can try a slide and the various tunings on a regular acoustic to see if playing like that is for you or not.
Whatever you do, just have fun and keep on playing.
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