Inflation is dipping, but rising rents are keeping it sustained.

The U.S. Bureau of Labor Statistics (BLS) published its monthly Consumer Price Index (CPI) report on Wednesday, tracking the changes in prices that Americans have to pay for essential goods and services, like shelter, food, and energy.

The CPI gauges purchasing power, or how far the dollar now goes compared to a year or a month ago.

It is the most broadly used measure of inflation; the Federal Reserve Board, the President, and Congress use the CPI as an economic indicator to help set policies. ^{Jerome Powell, chairman of the US Federal Reserve. Photographer: Al Drago/Bloomberg via Getty Images}

Here are three things things to know:

1. Prices rose 3.3% in May compared to a year ago but were flat month-to-month.

This is good news: Inflation has slowed down for the second month in a row.

Overall prices also stayed flat after increasing 0.3% in April.

Related: CPI Report: Rising Rent, Gas Prices Keep Inflation Up

When food and energy prices are taken out of the equation, prices rose 0.2% on the month and 3.4% from last year, which is still lower than analyst estimates.

2. Rent raises were the “largest factor.”

Rent prices, and owners’ equivalent rent, increased by 0.4% from April to May across the country, offsetting a 3.6% decrease in gas prices. This marks the fourth consecutive month that shelter prices were up that much.

Rent was “the largest factor” in overall inflation outside of food and energy and rose 5.4% from last year.

3. Rent wasn’t the only factor.

Other categories besides shelter have noticeably increased in price over the past year.

Car insurance, for example, went up by 20.3% while medical care went up by 3.1%.

From month-to-month, the prices of used cars and trucks rose 0.6% after decreasing by 1.4% in April.

Related: RealPage Rent Price-Fixing Probe Escalates With FBI Raid

Will the Fed lower interest rates?

The Fed will release a policy statement at 2 p.m. ET Wednesday after a two-day meeting on inflation, unemployment, and expected interest rates.