Help with Ruy Lopez please!

Hi, could someone please explain to me why 4...b5 is considered inaccurate and why moves like 4...Nf6 are preferred?

Thanks,

--k4sp4rov9--

It is not inaccurate, just less common. Andrew Greet has two chapters on 4...b5 in his book, Play the Ruy Lopez.

It is considered inaccurate because ...b5 is too early. It weakens the queenside where Black pieces are not yet ready for open position (White can open the position with d4). But this is only theoretical consideration where the mainline is the one  to be considered the more accurate :)

Below 2000, if you don't know much about Ruy Lopez, if you're not good with tactics, if you're not good with strategy/positional game, but you're good with endgame, 4...b5 followed by 5...Na5 and 6...Nxc3 (Norwegian Defense) is the best!

For a beginner you get away from develop major pieces first.