Investigatory Powers Bill: What is Theresa May going to announce today?

Internet firms will be required to store details of people's web usage for 12 months under proposed new spying laws being unveiled by the Home Secretary today.

The draft Investigatory Powers Bill will set out what powers the UK government will have to monitor communications between citizens.

Attempts to introduce the Bill - known as the 'Snooper's Charter' - failed in 2013 over a lack of parliamentary support.

Here's what we know about today's announcement.

• What exactly is the Investigatory Powers Bill?

It aims to overhaul the surveillance powers of the police and intelligence agencies in tackling terrorism and serious crime in the digital age.

It concerns, among other things, the interception of people's electronic communications.

Or according to the Government, "the ability of intelligence agencies and law enforcement to target online communications of terrorists, paedophiles and other serious criminals".

• Why does the Government want this new Bill?

It thinks the current legislation is out of date and that communication between terrorists, which increasingly takes place online, has become difficult to monitor.

Current legislation is also patchy and quite complicated, with different laws covered by different powers. The new Bill aims to bring the powers under one legal umbrella for the first time.

• What is the Home Secretary set to announce?

She will be announcing new proposals requiring internet and phone companies to keep data about people's online activity for up to a year.

Police and security services will be able to access most of that data without a warrant, although the specific pages viewed would not be accessible. For example, police could see that someone visited www.itv.com but would not be able to see the individual pages they viewed.

Councils, which can request communications data, will be banned from accessing people internet records.

The Bill is expected to introduce a role for judges in the process for authorising the more intrusive capabilities, and a senior judge will be appointed to the newly-created role of Investigatory Powers Commissioner to hold security services and police to account.

A new criminal offence of unlawfully obtaining data from a telecommunications operator will be created to prevent abuse by public authorities. It will carry a maximum sentence of two years in prison.

Security services will retain the capacity to intercept the content of communications after obtaining a warrant.

• What is not in the Bill?

Ministers have ruled out any attempt to ban encryption, which was argued would have limited Britain's role as a global business centre. However, there are concerns that it risks leaving authorities locked out of some areas of cyberspace.

A number of proposals from the abandoned 'Snooper's Charter' have been ruled out, such as powers to demand UK-based communications service providers (CSPs) to capture and store internet traffic from companies based in the US.

• Why is it controversial?

Many members of the public, privacy campaigners and government critics claim powers to intercept people's electronic communications are too intrusive.

They see it as a major extension of surveillance powers.

• Will the Bill get through Parliament easily?

The Conservatives now have the majority they did not have when the Communications Data Bill was ditched in 2013 after strong opposition from the Liberal Democrats.

However, the new laws are still likely to be controversial, with privacy campaigners, opposition MPs and backbenchers primed to examine its contents closely.