Geomorphology is the study of landforms and their processes, forms, and sediments at the surface of the Earth (and sometimes on other planets). Studying includes looking at landscapes to work out how the earth's surface processes, such as air, water, and ice, can mould the landscape. Landforms are produced by erosion or deposition, as rock and sediment are worn away by these earth-surface processes and transported and deposited to different localities. The different climatic environments produce different suites of landforms. The landforms of deserts, such as sand dunes and ergs, are a world apart from the glacial and periglacial features found in polar and sub-polar regions. Geomorphologists map the distribution of these landforms so as to better understand their occurrence.

Earth-surface processes are forming landforms today, changing the landscape, albeit often very slowly. Most geomorphic processes operate at a slow rate, but sometimes a large event, such as a landslide or flood, occurs, causing rapid change to the environment and sometimes threatening humans. So, geological hazards, such as volcanic eruptions, earthquakes, tsunamis, and landslides, fall within the interests of geomorphologists. Advancements in remote sensing from satellites and GIS mapping have benefited geomorphologists greatly over the past few decades, allowing them to understand global distributions.

Geomorphologists are also "landscape-detectives,” working out the history of a landscape. Most environments, such as Britain and Ireland, have in the past been glaciated on numerous occasions, tens of thousands of years ago. These glaciations have left their mark on the landscape, such as the steep-sided valleys in the Lake District and the drumlin fields of central Ireland. By studying the remaining landforms and the sediments, geomorphologists can piece together the history of such places by studying the particles and the organic material, such as pollen, beetles, diatoms, and macrofossils preserved in lake sediments and peat, can provide evidence of past climate change and processes.

So geomorphology is a diverse discipline. Although the basic geomorphological principles can be applied to all environments, geomorphologists tend to specialise in one or two areas, such as aeolian (desert) geomorphology, glacial and periglacial geomorphology, volcanic and tectonic geomorphology, and even planetary geomorphology. Most research is multi-disciplinary, combining the knowledge and perspectives from two contrasting disciplines, combining subjects as diverse as ecology, geology, civil engineering, hydrology, and soil science.