We can tune the case sensitivity of Vim's search globally or on a per-search basis.
Setting Case Sensitivity Globally We can make Vim's search patterns case insensitive by enabling the 'ignorecase' setting. But this setting has a side effect that influences the behavior of Vim's keyword autocompletion.
Setting Case Sensitivity per Search
\c: causes the search pattern to ignore case.\C: forces case sensitivity.
Enabling Smarter Default Case Sensitivity
If our pattern include an uppercase character, 'smartcase' canceling out the 'ignorecase'. If our pattern include all lowercase, the search will be case insensitive.