Here's it in a nutshell from the BBC
The prime minister has said he does not believe another national lockdown would be the "right course" in combating the pandemic
Instead a new, three-tiered lockdown system will be rolled out, categorised under medium, high and very high
Most areas in England will be put on a medium alert level - meaning current restrictions continue, including the 10pm hospitality curfew
But areas which already have local restrictions on household mixing will be automatically put on high alert. Under this category, social mixing will be prohibited indoors and in private gardens, and many businesses will be closed including pubs, gyms and casinos. The Liverpool City Region will become the first area to enter the very high alert level
The prime minster has also said that all retail outlets, schools and universities will remain open.