Most users are familiar with word navigation, for moving the caret to the next or previous word: Control-Left/Control-Right on Windows and Linux, and Opt-Left/Opt-Right on Mac. A previous post discussed the different modes for word breaking.
A less well-known features is “subword” navigation, which is very similar, except that it breaks in more places, such camelCase boundaries within words and underscores within identifiers. This is really useful for modifying parts of identifiers precisely. The keybinding is Alt-Left/Alt-Right on Windows and Linux, and Control-Left/Control-Right on Mac. As with word navigation, they can be combined with the Shift modifier to modify the current selection range.