Can someone explain to me what is global warming in their own words?

Global warming is the end to some things, and the beginning to others. Here are a few examples, some butterflies, foxes, and alpine plants have moved farther north or to higher, cooler areas. For some people this could be good and bad. Another reason, Ice is melting worldwide, especially at the Earth's poles. This includes mountain glaciers, ice sheets covering West Antarctica and Greenland, and Arctic sea ice. This also could be good for us to discover more species, or bad. It depends on our ecosystem. Global warming can cause weather changes, melting glaciers and sea ice, shifting precipitation patterns, and setting animals on the move.