Black Sabbath first band to create Metal and spawn its first sub-genre Doom Metal.
The band aimed to make horror music with heavy riffs.
the structure of this song is :
Verse 1
Verse 2
Instrumental break
Verse 3
Guitar solo
The song is played in C# tuning which is 1 and a half steps down from standard tuning, doing so it gives it a deeper tone.
Examples of doom metal
Example of stoner metal