Imagine you want to make a pretty bracelet using a bunch of beads. You start by tying a knot in one end of a long piece of string, and then you add beads one by one by pushing them onto the string until you have the length you want. The string that you used to put the beads on is like a thread.
In art, sometimes artists use a similar process to make their artwork. Instead of beads and string, they might use different materials like paints, pencils, or yarn. They use a special kind of thread called a "line" to make their artwork. A line is a long, thin mark that the artist puts on paper or canvas or another surface.
The artist might draw a line that is straight or curvy or jagged. They might use different colors or thicknesses of line to make their artwork interesting. They can make all sorts of things with lines - they can make a picture of a person, an animal, or a landscape, or they can make something totally abstract that doesn't look like anything in real life.
In art, the thread of lines is really important because it can show different emotions or feelings. A line that is smooth and flowing might make you feel calm or peaceful, while a line that is sharp and jagged might make you feel scared or uneasy. When you look at an artwork, try to pay attention to the lines - they can tell you a lot about how the artist was feeling when they made the artwork.