Where an analyst follows a user around, making notes on how they do their job. They observe the user in their natural environment to see exactly how the system works. One advantage is that the analyst sees parts of the system that the user may not realise are important. It can also confirm information gathered through other analysis. One disadvantage is that some people may feel threatened, and there is no guarantee that somethings may not be picked up, or the analysis may misunderstand something.

Interviewing

Where an analysis picks some key stakeholders and asks them targeted questions about the current and new system. One advantage is large amounts of info can be gathered and the analysis can discuss with the stake holder if they need clarification. It produces detailed responses about key parts of the system. One disadvantage is that it is very time consuming so only a limited number of people can be interviewed. Interviewees may not be truthful, so their responses need to be verified.

Lexical analysis removes comments and whitespaces, checks variable names, and turns the source code into a token stream.

Syntax analysis checks the order of expressions, reports errors in syntax and creates a syntax tree.

Machine code generation replaces nodes on the syntax tree with blocks of machine code, and optimises the machine code to improve run speed or file size.