 This concept is similar to the mechanism by which many word processors allow styles to be defined globally for an entire document, or the use of Cascading Style Sheets in styling HTML documents.The LaTeX system is a markup language that handles typesetting and rendering, and can be arbitrarily extended by using the underlying macro language to develop custom macros such as new environments and commands.Such macros are often collected into "packages," which could then be made available to address some specific typesetting needs such as the formatting of complex mathematical expressions or graphics (e.g., the use of the codice_1 environment provided by the codice_2 package to produce aligned equations).