Below, notice how kerning reduces the large gaps between certain letter pairs, making them consistent with the rest of the font.
Always use kerning. If you use paragraph and character styles, turn on kerning as part of your style definitions.
text-rendering: optimizeLegibility, and enable the OpenType feature
Professional page-layout programs make it possible to manually kern letter pairs. For professional typographers, this is a mandatory skill, but for everyone else, the built-in kerning is adequate.
See metrics vs. optical spacing for a special note about how Adobe InDesign handles kerning.