We were all taught how to cross a street: Look both ways. But, in some cities, you'll also have to ask permission by pressing a tiny button and waiting your turn. Those little buttons on walk signals have been nicknamed "beg buttons"—because walkers are pretty much begging to be able to cross.
Here in Los Angeles, if you don't press them, you won't even get the opportunity to cross—the light will turn red, stopping the opposing traffic, but you'll never get a walk signal and the light won't stay green long enough for you to actually make it to the other side.
It's annoying for walkers: have you ever tried to walk a few blocks, stopping to hit the button at every single intersection? Or hit the button just a few seconds too late and had to wait a whole additional cycle? But it also illustrates the backwardness of our street design: pedestrians, who are supposed to have the right-of-way, are required to press a button at an intersection in order to get a walk signal, which should happen automatically. This video illustrates the problem well:
This struggle is nothing new, of course. The term "jaywalking" was invented by the auto industry to shame pedestrians in the 1920s. But it has become an issue again due to recent, highly publicized crackdowns on jaywalking in Los Angeles and New York City. As reported a few weeks ago, offenders are being issued tickets upwards of $200. (That's actually not all that bad compared to some other places: In Singapore you could go to jail for three months.)