This paper presents the potential of Raman spectroscopy, a non-destructive technique which can be applied in situ, for the analyses of glass and its alteration. Recent analytical developments are summarised for different glass compositions and practical examples are given. The paper describes how to extract compositional information from the glass, first based on the spectrum profile to rapidly distinguish alkali silicate from alkaline-earth alkali silicate and lead alkali silicate glass, then using the spectral decomposition and correlations to extract quantitative data. For alkali silicate glasses, which are most prone to alteration, the spectral characteristics of the different alteration processes (selective leaching or dissolution) in the Raman spectra of the altered glass are described. These new developments have greatly widened the potential of the technique and supplement well its previously documented ability to measure the thickness of the altered layer and identify crystalline deposits.