An acute angle* measures less than 90^. It looks like a sharp corner.

Here are the types of angles, building on the previous explanation:

• An acute angle measures less than $90^\circ$. It looks like a sharp corner.
• A right angle measures exactly $90^\circ$. It forms a perfect square corner, often indicated by a small square symbol at the vertex.
• An obtuse angle measures greater than $90^\circ$ but less than $180^\circ$. It looks wider than a right angle but not flat.
• A straight angle measures exactly $180^\circ$. It forms a straight line.
• A reflex angle measures greater than $180^\circ$ but less than $360^\circ$. It's the "outside" angle when two rays meet, encompassing more than a straight line.