The Dictionary panel is a special help panel which contains information about all standard functions, constants and variables. It displays a short comment about the function, variable or constant. You can find Dictionary panel inScripts->Dictionary. The Dictionary window is shown on the right hand.

 As you can see, the Dictionary shows information for the four supported languages: ProTrader Language (native), MQL2, MQL4, EasyLanguage. Select appropriate language to see the list of available functions.  Functions, Constants and Variables are displayed as tree nodes. Nodes are further divided into sub-nodes according to each usability package.

Note: Platform functions which we recommmend to use .NET languages are located in ProTraderLanguage section.

To expand all groups to show their subgroups, click the Expand All button. To collapse all groups showing their subgroups, click the Collapse All button.

Favorites includes user's favorite functions, constants and variables. If you want to add functions to favorites, select the function, constant, or variable name in the Dictionary and right-click to open the context menu and select Add to Favorites.

You can filter functions using advanced criteria of Dictionary panel.

Double-click on each item for html description. Here you can find function prototype, description, parameters explanation and example. 
 

Note: Only MQL functions have a full html description. For the rest of functions you can see only short desctiption with prototype in Dictionary: