To obtain results in automatically treating natural languages, these will often be approached as formal languages although natural languages are a lot more complex. In this book the main problems related to the semantics of natural language are reviewed. Also, the book presents various topics such as: the stages of communication in natural language, formal grammars for syntactic analysis, an idea for syntactic analysis based on morphological features of the language, types of ambiguity, lexical disambiguation algorithms, Wordnet and a library for accessing Wordnet by programmers, a Delphi implementation of a parser using CKY algorithm, logical formalisms for the semantics of natural language, discourse theory, conceptual dependency theory, bivalent verbs and pragmatics related problems. Some original results and studies about Romanian are included. The book contains some source codes and algorithms.