When isobars enclose an area of high pressure this is called a High and its centre is labelled on a weather map by an 'H'.

Another name for a High is an anticyclone.

Near a High's centre are light winds and sometimes areas of low cloud.

Round the edge of a High, the winds are sometimes strong. Winter Highs often bring frost; summer Highs may bring thunderstorms and hail.

The bigger Highs are, the slower they tend to move, sometimes 'blocking' the fronts that are trying to follow them.

When isobars enclose an area of low pressure this is called a 'low' and its centre is labelled on a weather map with an 'L'.

Another name for a Low is a depression.

A low pressure system is like a giant funnel of wind spiralling inwards and upwards forcing warmish air in the centre to rise. As air rises it cools and clouds form.