“I'm lovin' it” was the name and central phrase of McDonald's first global advertising campaign using that wording.
McDonald's launched the campaign in 2003, making it the company's first global advertising campaign. The lowercase styling and “ba da ba ba ba” musical hook became closely associated with the brand in television, radio, print, and digital advertising.
The campaign was adapted for different markets and languages, but the English phrase remained one of the most recognizable elements of McDonald's modern identity. It succeeded earlier slogans that had been used more selectively or in particular countries.
The campaign's creation is sometimes simplified into a claim that McDonald's invented the phrase itself. The wording had an earlier connection to a song and advertising work before McDonald's adopted it, but McDonald's made the phrase globally famous. This question concerns the campaign title, not a menu item or company motto.