If you do write down your passwords, don't make it obvious which password corresponds to which account. Even better, write the passwords incorrectly and make up an easy rule for fixing them. You could decide to add 1 to each number in your password, so that 2x6Y is written as 3x7Y.

Suppose a bad guy guesses the password for your throwaway Yahoo address. Now he goes to major banking and commerce sites and looks for an account registered to that email address. When he finds one, he clicks the 'forgot my password' button and a new one is sent - to your compromised email account. Now he's in a position to do you serious harm.

Google appears to be the worst of the major search engines from a privacy point of view; Ask.com, with AskEraser turned on, is among the best.

The best way to preserve your privacy is to use a search engine that does not keep your logs in the first place. That's the approach used by Startpage and its European parent company, Ixquick.

Everyone and his Big Brother wants to log your browsing habits, the better to build a profile of who you are and how you live your life - online and off. Search engine companies offer a benefit in return: more relevant search results. The more they know about you, the better they can tailor information to your needs.

You don't need to be a spook to care about encryption. If you travel with your computer or keep it in a place where other people can put their hands on it, you're vulnerable.

Most computers today have built in backup software.

For personal use, I recommend the free and open-source Truecrypt, which comes in flavors for Windows, Mac and Linux.

Nothing is absolute in security.

I've always shied away from online data storage. I don't even use my employers' network drives for anything sensitive. I want to control access myself.

Cloud services cut both ways in terms of security: you get off-site backup and disaster recovery, but you entrust your secrets to somebody else's hands. Doing the latter increases your exposure to government surveillance and the potential for deliberate or inadvertent breaches of your confidential files.

Well-secured files don't do you much good if you lose them in a fire or hard drive crash.

I favor pocket-sized hard drives that travel between home and office, syncing with computers on both ends.

The Patriot Act unleashed the FBI to search your email, travel and credit records without even a suspicion of wrongdoing.

I learned the technology and tradecraft of electronic security in self defense, with a lot of expert help.

As Trotsky didn't exactly say, you may not be interested in electronic snoops, but snoops are interested in you, whether or not you keep Coke's secret recipe on your iPhone.

Privacy is relational. It depends on the audience. You don't want your employer to know you're job hunting. You don't spill all about your love life to your mom or your kids. You don't tell trade secrets to your rivals.

Friend of mine, a smart journalist, had his iPad stolen. He couldn't help that - the thief broke into his house. But his private, personal data wasn't stolen, exactly. Donated, more like. He had no passcode set on the iPad.

A minimum precaution: keep your anti-malware protections up to date, and install security updates for all your software as soon as they arrive.

It no longer counts as remarkable that Egyptians organized their uprising on social media.

Activists and geeks, standing together, are demonstrating powers beyond the reach of government control.

Federal prosecutors want to indict Julian Assange for making public a great many classified documents.

The Obama administration, like those before it, promotes a disturbingly narrow interpretation of the Fourth Amendment, misapplying the facts of old analog cases to a radically different digital world.

Companies that receive government information demands have to obey the law, but they often have room for maneuver. They scarcely ever use it.

We know what's in our Cheerios and in our retirement accounts because the law requires disclosure.

Dell fills its computers with crapware, collecting fees from McAfee and other vendors to pre-install 'trial' versions.

Given the volume of PC sales and the way McAfee runs its operation, I imagine there must be thousands of phantom subscribers - folks who signed up once upon a time and left the software behind two or three computers ago.

First developed as a weapon by the U.S. Army, VX is an oily, odorless and tasteless liquid that kills on contact with the skin or when inhaled in aerosol form. Like other nerve agents, it is treatable in the first minutes after exposure but otherwise leads swiftly to fatal convulsions and respiratory failure.

The United States, a signatory to the Chemical Weapons Convention, destroyed the last of its stocks of VX and other chemical agents on the Johnston Atoll, 825 miles southwest of Hawaii, in November 2000.

The U.N. Security Council ordered Iraq in April 1991 to relinquish all capabilities to make biological, chemical and nuclear weapons as well as long-range missiles.

During the morning rush hour on March 20, 1995, the Japanese cult Aum Shinrikyo placed packages on five subway trains converging on Tokyo's central station. When punctured, the packages spread vaporized Sarin through the subway cars and then into the stations as the trains pulled in.

Smallpox, which spreads by respiration and kills roughly one in three of those infected, took hundreds of millions of lives during a recorded history dating to Pharaonic Egypt. The last case was in 1978, and the disease was declared eradicated on May 8, 1980.

The U.S. government has known since the early 1990s about Soviet-era smallpox weapons, and collected circumstantial evidence of programs elsewhere.

The CIA now assesses that four nations - Iraq, North Korea, Russia and, to the surprise of some specialists, France - have undeclared samples of the smallpox virus.

For political and bureaucratic reasons, governments at all levels are telling far less to the public than to insiders about how to prepare for and behave in the initial chaos of a mass-casualty event.

Nearly all government advice on terrorism sacrifices practical particulars for an unalarming tone. The usual guidance is to maintain a three-day supply of food and water along with a radio, flashlight, batteries and first-aid kit.

Unsettling signs of al Qaeda's aims and skills in cyberspace have led some government experts to conclude that terrorists are at the threshold of using the Internet as a direct instrument of bloodshed.

Counterterrorism analysts have known for years that al Qaeda prepares for attacks with elaborate 'targeting packages' of photographs and notes.

Experts said public companies worry about the loss of customer confidence and the legal liability to shareholders or security vendors when they report flaws.

Ordinary Geiger counters, worn on belt clips and resembling pagers, have been in use by the U.S. Customs Service for years.

Searches of al Qaeda sites in Afghanistan, undertaken since American-backed forces took control there, are not known to have turned up a significant cache of nuclear materials.

There is evidence that some of al Qaeda's nuclear efforts over the years met with swindles and false leads.

Al Qaeda is closely aligned with the Chechens.

White House officials acknowledge in broad terms that a president's time and public rhetoric are among his most valuable policy tools.

The government of Sudan, employing a back channel direct from its president to the Central Intelligence Agency, offered in the early spring of 1996 to arrest Osama bin Laden and place him in Saudi custody, according to officials and former officials in all three countries.

Sudan expelled bin Laden on May 18, 1996, to Afghanistan.

The consumption and production of energy is a major component of the global economy.

How are the cabs in your city? In Manhattan, where I work, they are rather awful.

In New York, the former lack of real competition allowed taxis to extract excessive charges, regardless of the poor service.

The way we finance homes in this country is slow, filled with middlemen, who run a nonstandardized evaluation process. This makes financing a home cumbersome and difficult.