diff --git a/src/data_types.hpp b/src/data_types.hpp
index 49406ea..cbe6faf 100644
--- a/src/data_types.hpp
+++ b/src/data_types.hpp
@@ -13,14 +13,18 @@
 
 class Monitor;
 
+/** @brief The possible item value types */
 using Value = int64_t;
 
+/** @brief A list of what constructs a unique item and its value */
 using Group = std::vector<std::tuple<std::string, Value>>;
 
+/** @brief A conditional function type for item(s) conditions */
 using Condition = std::function<bool(sdbusplus::bus::bus&,
                                      sdbusplus::message::message&,
                                      Monitor&)>;
 
+/** @brief A void function type for actions based condition(s) */
 using Action = std::function<void(sdbusplus::bus::bus&,
                                   Monitor&)>;