Seeing nanometer-sized world -- Structure and imaging of a transmission electron microscope (TEM) -- Basic theories of TEM imaging -- Resolution and image contrast of a transmission electron microscope (TEM) -- What is high-resolution transmission electron microscopy ? -- Lattice images and structure images -- Imaging theory of high-resolution TEM and image simulation -- Advanced transmission electron microscopy -- What is scanning transmission electron microscopy (STEM)? -- Imaging of scanning transmission electron microscopy (STEM) -- Image contrast and its formation mechanism in STEM -- Imaging theory for STEM -- Future prospects and possibility of TEM and STEM -- Concluding remarks -- Introduction of Fourier transforms for TEM and STEM -- Imaging by using a convex lens: Convex lens as phase shifter -- Contrast transfer function of a transmission electron microscope: Key term for understanding of phase contrast in HRTEM -- Complex-valued expression of aberrations of a round lens -- Cowley's theory for TEM and STEM imaging -- Introduction to the imaging theory for TEM including non-linear terms -- What are image processing methods? -- Elemental analysis by electron microscopes: Analysis using an electron probe -- Electron beam damage to specimens -- Scattering of electrons by an atom: Fundamental process for visualization of a single atom by TEM -- Electron diffraction and convergent beam electron diffraction (CBED): Basis for formation of lattice fringes in TEM and image intensity of STEM -- Bethe's method for dynamical electron diffraction: Basic theory of electron diffraction in thicker crystals -- Column approximation and Howie-Whelan's method for dynamical electron diffraction: Theory for observation of lattice defects -- Van-Dyck's method for dynamical electron diffraction and imaging: Basis of atomic column imaging -- Eikonal theory for scattering of electrons by a potential -- Debye-Waller factor and thermal diffuse scattering (TDS) -- Relativistic effects to diffraction and imaging by a transmission electron microscope: Basic theories for high-voltage electron microscopy.