First of all, I want to thank you for such a remarkable site that not only strives to provide accurate information but beautiful photos as well. Thanks to your site, my 5 year old daughter is coming full circle from screaming about a mere gnat buzzing around her to giggling with delight upon discovering some "scary but interesting bug" on her swingset. This spider showed up in our Los Angeles home and I still have yet to be able to identify it. It wasn’t all that large, perhaps the length of my tip of my pinkie finger if that. Lots of fine hairs on the legs and body too. Thanks again for your wonderful site!
Thanks for resending the photo. Our guess was correct. This is a Phidippus Jumping Spider, probably Phidippus formosus. Jumping Spiders have excellent eyesight, and do not build webs. They stalk and leap at their prey. They will often follow the movement of a human, constantly turning to face the much larger being.