A Lifeworld indicates the activities of a living agent, as that agent lives them, not as an external observer views them. We speak of a lifeworld as seating, instituting, and rendering the actuality of phenomenal experience. A life takes place in its lifeworld; lived lives happens in and through its lifeworld.
Why don't we just speak about the world, plain and simple, without qualifying it as the lifeworld? Isn't the world always there, waiting for us with look and listen? But as soon as we start to think about the presence of the world, we recognize that the greatest proportion of it is clearly, always, out of sight, far beyond ear shot. And even what's right here before my eyes, looks very different to you, before your eyes over there. At the very least, the world right there before us brings many relativities and obscurities with it.
Through much of cultural life, context served to make sense of many perspectives on the world. And clever thinkers sent ingenious effort to find precisely what was common to all the appearances.