# Data Types and Data Forms {#chap4_sect_datatypes_forms}

The DolphinDB system allocates memory and decides what to be stored in the reserved memory based on the data type of a variable. This chapter introduces data types, categories, and forms are first summarized in a table and then explained with examples. The codes and results in the paragraphs with light gray background are the same as seen from a console. Users can copy and paste these codes to a console, execute and then check the results.

