AT&T has announced it's buying DirecTV in a $49 billion deal — an enormous acquisition that could turn one of the nations top telecom companies into a formidable player in the pay-TV market. And the agreement is sure to be examined closely by federal regulators.

To help win their approval, AT&T is offering to abide by net neutrality principles for three years: the company would not block Web sites; it would also not discriminate against certain Web content by slowing down or speeding up different lanes of Internet traffic to customers.

Post tech reporter Hayley Tsukayama explains the idea of net neutrality and why its future could affect every Internet user. (Davin Coburn/The Washington Post)

The commitment uses as its standard not the new net neutrality regulations being designed right now by the Federal Communications Commission, but rather the commission's old rules that were implemented in 2010 and subsequently struck down by a federal court in January. AT&T says it'll respect the old regulations no matter what the FCC's new proposed rules on net neutrality wind up looking like. Critics say the agency's current plan doesn't go far enough.

AT&T's net neutrality commitment follows in the footsteps of another media giant, Comcast. In 2011, Comcast agreed to uphold the 2010 FCC rules as a condition of its agreement to buy NBC Universal.

AT&T's terrestrial broadband service, U-Verse, currently reaches only about 25 percent of the country, according to analyst Craig Moffett. And AT&T's net neutrality commitment will likely not apply to mobile broadband, as the 2010 rules excluded the wireless industry.

But consumer advocates were quick to cast skepticism on AT&T's offer.

"If this is the perk of an acquisition, why is it ending after three years?" said Bartees Cox, spokesman for the public interest group Public Knowledge.