I seem to have more reads after alignment than before.

Before alignment

` awk '{s++}END{print s/4}' reads.fastq `
> 153265

After alignment

`samtools flagstat align.bam`
> 180051 + 0 in total (QC-passed reads + QC-failed reads)

> 0 + 0 secondary

> 26786 + 0 supplementary

> 0 + 0 duplicates

> 171567 + 0 mapped (95.29% : N/A)

> [...]

I do not understand how can that be. 

Can you help?
the bam contains the **supplementary** (part of the read that maps elsewhere) + **secondary**  (some other probable hits for the read) alignments