(
DVD-Recordable)  A write-once (read only) DVD disc for both movies and data endorsed by the DVD Forum.  DVD-Rs are often called "DVD Dash Rs" or "DVD Minus Rs" to distinguish them from the competing "Plus R" format (see 
DVD+R).
DVD-Rs are the DVD counterpart to CD-Rs and use the same dye-layer recording technology to "burn" the disc.  Pioneer was the first to introduce DVD-R drives, which recorded 3.95GB.  By 2000, the capacity was increased to the industry standard 4.7GB.  A dual-layer drive (DVD-R DL) increases capacity to 8.5GB.
In practice, the term "DVD" refers to all DVD formats.  The phrase "burn the DVD" really means "burn the DVD-R or DVD+R."
DVD-R for Authoring, DVD-R for General
In 2000, DVD-R was split into two types to deal with copy protection.  The original DVD-R, which uses a 650 nm recording wavelength, was dubbed "DVD-R for Authoring."  A different format with copy protection that records at 635 nm is called "DVD-R for General."  Although DVD-R(a) and DVD-R(g) can read each other's format, they cannot write each other's format.
A Small Fortune in the Beginning
DVD-R machines (DVD burners) cost as much as $17,000 in their first incarnations back in 1997 but dropped to less than $25 two decades later.  See 
DVD, 
DVD storage capacities, 
DVD+R, 
CD-R and 
optical disc.
A DVD Writer
Modern DVD drives support all the DVD formats as the specs for this Slim External DVD Writer from LG indicate.