Solitaire Classic Klondike is the solitaire almost everyone means when they say solitaire — the one that shipped with Windows and taught a generation to use a mouse. Build four foundation piles by suit from ace to king, using a tableau you stack in descending order with alternating colours.
It's a better game than its ubiquity suggests. Not every deal is winnable, and the winnable ones usually require prioritising the face-down cards over moves that look tidier.
Prioritise moves that reveal face-down cards over ones that simply tidy the tableau, and don't send low cards to the foundations too early — you often need them to build on.
No. A meaningful fraction of Klondike deals are unwinnable regardless of play, which is worth knowing before blaming yourself.
Yes — tap or drag cards. Nothing to install.