Communities across the UK will make a show of support for servicemen and women as the country celebrates Armed Forces Day.
More than 100 events, ranging from veterans' parades and bands to barbecues and fairs, will be held at the culmination of a week of tributes to British troops and their families.
The day is marked to raise awareness of the contribution made by the Army, Navy and RAF, and to allow the public to demonstrate their appreciation.
Prime Minister David Cameron said: "Today is an opportunity for everyone up and down the country to clearly show how grateful we are to all our brave servicemen and women for all that they do.
"It's also vitally important that we remember the sacrifices that the armed forces and their families make every day for the safety of our country."
The celebration comes as military charities report a 26% increase in donations since the beginning of the economic crisis in 2008.
Help for Heroes saw a 181% gain in income, while Support Our Soldiers, which sends care parcels to the frontline, saw an 87% increase, according to The Sun.
A national event will be held in Plymouth, where there will be a parade through the city by members of all three services, joined by military bands and veterans. The parade will finish on the Plymouth Hoe with a drumhead service, although entertainment will continue throughout the day.
Deputy Prime Minister Nick Clegg said: "Today I'm joining the rest of the country in saying thank you to our armed forces. We owe our servicemen and women a huge debt of gratitude for their dedication, resilience and sacrifices."
Mr Clegg said the celebrations should "go some way to showing how grateful we are for the work of all our armed forces and how much we recognise their contribution".