The language of economics and the financial system can be confusing for those not steeped in the world of pensions, gilts and bear markets.

But there’s been a lot of around, as the Conservative Party’s mini-budget spooked the markets, causing a collapse in the pound and a surge in the UK’s borrowing costs. Here’s an explanation to some of the phrases and ideas being bandied around.

The economic theory is highly fashionable having been fully embraced by the UK’s new prime minister, Liz Truss and her chancellor, Kwasi Kwarteng, in their controversial “fiscal event”.

The theory holds that the supply of goods and services within the economy is the main driver of growth. Put bluntly, the idea is to give wealthy individuals or large corporations tax cuts, which in turn creates jobs and later increases the number of people paying taxes and boosts the amount of money collected by the Treasury. The prime minister’s approach has been dubbed “Trussonomics”, and supporters talk a lot about baking a bigger economic “pie” that everyone can share.

The theory was particularly popular in right-wing circles in the 1980s. In common with US president Ronald Reagan, UK prime minister Margaret Thatcher experimented in this kind of low-tax economics, the results of which have been disputed ever since.

The phrase “trickle-down” economics – the benefits generated at the top trickling down to everyone – has become synonymous with the idea.

When talking about supply-side economics, commentators will invariably refer to the Laffer Curve – a graph showing the relationship between tax rates and the amount of tax revenue collected by governments. It’s named after Arthur Laffer, a member of Reagan’s economic policy advisory board, who also advised Thatcher, earning him the nickname the “father” of supply-side economics.

A technical recession is defined by two successive quarters of falling economic output – measured by gross domestic product (GDP), which attempts to summarise all the activity of companies, governments and individuals in an economy in a single figure.

Some people argue the term “recession” is an unreliable indicator because people could be suffering all the effects of an economic downturn, such as long-term unemployment, but the data might not officially say as much.

Kwarteng has admitted the UK is “technically” in a recession, even if the official figures are yet to confirm it.

In 2020, the Office for National Statistics (ONS) officially declared the UK in recession – the steepest on record – after the economy plunged by 19.6% between April and June due to the coronavirus lockdown.

It followed a 2.2% contraction in the previous three months – marking the first recession since the 2008 global financial crisis, when the UK fell into a year-long recession.

At its heart, inflation is the measure of how quickly the cost of goods and services is growing. It is an average across many categories, so if food prices rise, that could still be offset by drops in, say, the price of petrol.

In the UK, the ONS is tasked with estimating the inflation rate.

It has a basket of goods and services that it tracks. It might be helpful to think of this as a massive shopping basket with what the ONS thinks that people in the UK buy. It includes around 730 items, anything from dating agency fees to condoms, wild bird seed to petrol, and crumpets to pet food.

What is in the basket changes every year – with some additions and some removals – because what people buy changes. For 2022 antibacterial surface wipes were added, along with meat-free sausages and other items.

Owned by but independent from the UK government, the Bank of England is tasked with keeping inflation under control, targeting 2% a year.

But in recent months inflation has started to run away. It hit 9.9% in August and, despite government action to freeze energy bills, is still expected to strike a new 40-year-high “just below 11%”, the central bank has said.

The Bank of England also has a wider remit to ensure the health of the economy. Many will remember the economy-boosting stimulus in the form of quantitative easing – often referred to as printing money – being deployed during the 2008 financial crisis.

An interest rate is a measure that tells you how high the cost of borrowing money is, or how high the rewards are for saving.

The Bank of England’s “base rate” – the interest rate at which banks borrow from the central bank, which has billions of pounds in assets at its disposal – has a knock-on effect on the interest rates offered on the high-street for mortgages and savings.

Raising and lowering interest rates is the blunt instrument at the Bank’s disposal to control the economy. Hiking the base rate increases the cost of borrowing, making both credit and investment more expensive. The idea is to put the brakes on the economy and curb soaring inflation. Bringing rates down is an attempt to have the opposite effect – stimulate growth by making borrowing cheaper, and in turn, encourage investment.

Before the mini-budget, the Bank raised the base rate by 0.5 percentage points – the seventh hike since December – in a bid to keep inflation under control. Now some analysts are predicting the base rate, currently standing at 2.25%, will have to rise to as high as 6% next year.

The Bank of England has also intervened to try to bring surging yields in government bonds – known as gilts – under control as they spiralled higher, sending UK public borrowing costs soaring.

It said it would buy bonds “on whatever scale is necessary”. The Bank stepped in to calm markets after some types of pension funds were at risk of collapse.

Bonds are loans that investors make to a bond issuer and can be issued by companies or governments to raise money.

The yield on a bond is the amount of money an investor receives for owning the debt and is represented as a percentage of its price. When a bond price falls, its yield rises.

Yields fall when investors are less willing to own the debt, meaning they will pay a lower price for the bonds.

Alarm bells were ringing when yields on 10-year UK government bonds rose above 4%, the highest since the 2008 financial crisis, and more than triple the 1.3% rate at the start of the year.

The higher yield reflected fears investors had in the state of the UK economy, and again impacts how much interest banks charge for various types of loans, most notably mortgages.