Write the SMILES of 4-Vinylcyclohexene, C8H12: the structure is drawn for you, and the answer is marked on the molecule, not the string.
Convert between chemical structures and SMILES in both directions, search a list of structures by substructure or SMARTS, and learn the notation step by step. Everything runs in your browser — no structure you open ever leaves your machine — so the tool needs JavaScript.