Lamellipodia are thin, sheet-like extensions of the cell membrane that play a crucial role in cell movement. They are formed by the polymerization of actin filaments, which are proteins that provide structural support and facilitate cellular processes. Lamellipodia help cells crawl along surfaces, allowing them to migrate toward specific locations, such as during wound healing or immune responses. These structures are particularly important in embryonic development and cancer metastasis, where cells need to move and invade new tissues. The dynamic nature of lamellipodia enables cells to respond quickly to their environment, making them essential for various biological functions.