Your vocal range is the span of notes your vocal cords are capable of producing. Some people don’t know HOW to produce their high notes well, even though their vocal cords are capable of it.
The average range of a singer Is 3 to 3.5 octaves even though I’ve have seen ranges as small as 1.5 octaves to as large as 4.5 octaves.
The extreme notes at the edge of your range may never be beautiful and usable but if you vocalize from your lowest note to your highest note, you will definitely improve the quality and control of the pitches close to the extreme notes.
For pop singing, you should know your range and which songs are comfortable In which key. For musical theatre singing, it’s more Important to know your “voice classification” (Soprano, alto etc) and character strengths (e.g. dramatic soprano or lyric tenor) so you can realistically prepare for certain roles.
Although ranges vary from person to person, below are the approximate ranges for each voice type.
Keep exploring your range and remember to vocalize everyday from your lowest to your highest note for optimal range mobility!