The simplest level of analysis is Lexical analysis, which involves analysis of words. Words are most fundamental unit (syntactic and semantic) of any natural language text Word level processing require morphological knowledge i.e knowledge about structure and formation of words from basic units The next level of analysis is Syntactic analysis, which considers a sequence of words as unit i.e. A sentence and finds its structure. Syntactic analysis decomposes a sentence into words and identify how they relate each other.
This level of processing requires syntactic knowledge, i.e knowledge about how words are combined to form larger units such as phrases and sentences and what constraints are imposed on them. Example: I went to the market is a valid sentence whereas went I to the marke t is not . She is going to the market is valid whereas she are going to the market is not. This require detailed knowledge about the rules of Grammar.