Beams:

Before we move on let’s explore the beaming of notes. Connecting together the flags of eighth and sixteenth notes is called a beam. It simply means pairing up the notes so there isn’t a big long stream of individual notes. They would be hard to read, but instead, by grouping the notes they are much easier to read.

Compare the following:
8 eighth notes

8 sixteenth notes

Grouping provides a great way to easily read and recognize our rhythm pattern for these notes.