In this lecture, I will discuss how to use trapped ions for quantum information processing including quantum computation/simulation. The trapped ion system is one of the leading candidates for the practical quantum computer/simulator and nowadays many companies such asIonQ, Honeywell, Alpine Quantum Computer and so on, has been involved in developing their quantum computer with trapped ions. Here I will begin the lecture by introducing various type of ion traps mainly in Paul trap, then discuss the basic process of quantum computation as initialization, quantum gates, and detections. I will also bring out the difficulties and problems with current technology and discuss the technical and theoretical developments to address them. Finally, I will provide the outlook for the large scale quantum computation with trapped ions in near future, mostly related to the perspective of NISQ (noisy-intermediate scale quantum computing).