It refers to sequencing the entire genome of an organism, either de novo or reference based.
Resequencing is done for Genotyping and Variation analysis, with the help of known reference sequences.
De novo sequencing refers to sequencing a novel genome where there is no reference sequence available for alignment. Sequence reads are assembled as contigs, and the coverage quality of de novo sequence data depends on the size and continuity of the contigs (ie, N50 size and the number of gaps in the data).
Hybrid sequencing utilizes various approaches like short read sequencing, Long read sequencing, Genome Mapping, Chromosome conformation technologies to achieve accurate Genome assembly.
Mitochondrial DNA sequencing helps in Population Genetics and disease studies, as it is passed from mother to child and is responsible for a variety of diseases.