Everything in geometry starts with a simple, powerful idea: the point. A point isn't a thing you can hold. It's just a location. It has no size, no width, and no depth. Think of it as a single, precise spot in space, like a pinprick on a map.

Even though points are technically invisible, we need a way to see and talk about them. We represent a point with a dot and name it with a capital letter, like A, B, or C. This helps us keep track of different locations.

What happens when you connect an infinite number of points in a perfectly straight path? You get a line. A line has length but no width or thickness. It's a pure, one-dimensional object. The most important property of a line is that it extends forever in both directions. The arrows on either end of a drawn line show that it never stops.

We can name a line in two ways. The most common way is to pick any two points on the line, say point A and point B, and call it line AB. We write this as $\overleftrightarrow{AB}$. The arrows above the letters remind us that the line goes on forever. Alternatively, we can name a line with a single, lowercase letter, like line $l$.

Sometimes we don't need the entire infinite line. We might only be interested in a specific piece of it. This is where line segments and rays come in.

A line segment is a part of a line that is bounded by two distinct end points. It contains these endpoints and all the points on the line between them. Unlike a line, a line segment has a specific, measurable length. We name a line segment by its endpoints, like $\overline{AB}$. Notice there are no arrows this time.

A ray is a bit of a hybrid. It's a part of a line that has one endpoint and extends infinitely in one direction. Think of a ray of sunlight starting at the sun and traveling out into space. To name a ray, we use its endpoint and one other point on the ray. The notation is $\overrightarrow{AB}$, where A is the endpoint. The order matters here; $\overrightarrow{BA}$ would be a different ray starting at B and going in the opposite direction.

These basic elements—points, lines, segments, and rays—are the alphabet of geometry. Let's see if you've got them down.