Geometry stands for:
geo which means earth and metria which means measure.
A major contributor to the field of geometry was Euclid - 325 BC
who is typically known as the Father of Geometry and is famous for his works called The Elements. As one progresses through the grades, Euclidian geometry (Plane Geometry) is a big part of what is studied. However, non-Eucledian geometry will become a focus in the later grades and college math.
Simply put, geometry is the study of the size, shape and position of 2 dimensional shapes and 3 dimensional figures. However, geometry is used daily by almost everyone. In geometry, one explores spatial sense and geometric reasoning. Geometry is found everywhere: in art, architecture, engineering, robotics, land surveys, astronomy, sculptures, space, nature, sports, machines, cars and much more.
When taking geometry, spatial reasoning and problem solving skills will be developed. Geometry is linked to many other topics in math, specifically measurement and is used daily by architects, engineers, architects, physicists and land surveyors just to name a few. In the early years of geometry the focus tends to be on shapes and solids, then moves to properties and relationships of shapes and solids and as abstract thinking progresses, geometry becomes much more about analysis and reasoning.
Geometry is in every part of the curriculum K-12 and through to college and university. Since most educational jurisdictions use a spiraling curriculum, the concepts are re-visited throughout the grades advancing in level of difficulty. Typically in the early years, learners identify shapes and solids, use problem solving skills, deductive reasoning, understand transformations, symmetry and use spatial reasoning. Throughout high school there is a focus on analyzing properties of two and three dimensional shapes, reasoning about geometric relationships and using the coordinate system. Studying geometry provides many foundational skills and helps to build the thinking skills of logic, deductive reasoning, analytical reasoning and problem solving to name just a few.
Some of the tools often used in geometry include: Compass, protractors, squares, graphing calculators, Geometer's Sketchpad, rulers etc.
The grade by grade goals section (scroll down) will give more specific details of the geometry concepts expected in grades Pre-K to 12.