A selection may not be the quickest route to complete your task

Sometimes a selection might not be the quickest way around a task: there are other ways to get the job done. The Blend If command is a marvel. It works by letting us blend the pixels on one layer with those below, so effectively we can choose to hide or reveal pixels based on their color or luminosity. In practice, it’s very useful for tasks like knocking out a white background when you want to place an object onto a different image. Simply copy the image across, double-click the layer to enter the Blend If command, then drag the This Layer white point slider inwards to remove the white background from the image. If the blend looks jagged around the edges, hold Alt and drag half of the slider to split it up and create more of a gentler transition to the effect.