This book provides tools well suited for thequantitative investigation of semiconductor electron microscopy. These tools allow for the accurate determination of the composition of ternary semiconductornanostructures with a spatial resolution at near atomic scales. The bookfocuses on new methods including strain stateanalysis as well as evaluation of the compositionvia the lattice fringe analysis (CELFA) technique.The basics of these procedures as well as theiradvantages, drawbacks and sources of error are alldiscussed. The techniques are applied to quantumwells and dots in order to give insight intokinetic growth effects such as segregation andmigration. In the first part of the book the fundamentals oftransmission electron microscopy are provided.These are needed for an understanding of thedigital image analysis techniques described in thesecond part of the book. There the reader willfind information on different methods ofcomposition determination. The third part of thebook focuses on applications such as compositiondetermination in InGaAs Stranski--Krastanovquantum dots. Finally it is shown how animprovement in the precision of the compositionevaluation can be obtained by combining CELFA withelectron holography. This is demonstrated for anAlAs/GaAs superlattice.