Spacious, majestic, and often breathtakingly beautiful, glaciers store about 10% of the Earth's freshwater. These large ice masses play a crucial role in the Earth system by shaping landscapes and influencing climate on both regional and hemispheric levels, as well as having a significant impact on global sea levels. Over time, the Earth has experienced various major glaciations in its deep history, long before the Quaternary ice ages began, and the observed effects of climate change on glaciers have recently brought them into public awareness. This very brief introduction provides an overview of glaciers and ice sheets as systems, examining the role of geomorphology and sedimentology in their study, as well as their impacts on our planet in terms of erosive and sedimentary processes. David Evans explores the extent of our glaciers today and their ongoing processes.