This document discusses novel optical probes for intracellular sensing and imaging using Raman tags. It describes three main types of Raman tags: SERS probes, bioorthogonal Raman probes, and RR probes. SERS probes consist of Raman reporters conjugated to nanostructured gold or silver substrates and can target specific molecules. Bioorthogonal Raman probes use chemical bonds like alkynes that produce signals in the Raman-silent region to label molecules without background interference. RR probes enhance the Raman signal of reporter molecules through resonance excitation at their electronic transition wavelength, allowing specific targeting and high-contrast imaging of molecules. These Raman tag approaches enable quantitative, qualitative, and multiplexed analysis of intracellular processes with high sensitivity and minimal perturbation of living cells.