President Reagan has just returned from a trip to Western Europe, where he met such important world leaders as Prime Minister Margaret Thatcher of Britain in London, President Francois Mitterrand of France in Paris, and Chancellor Helmut Schmidt of West Germany in Bonn.
The American President also met with them and a few other world leaders at a special high-level meeting, called a summit, in Versailles, a short distance from Paris.
When the President travels abroad -- or any leader of any other country does so -- he is always greeted with pomp and ceremony. The same is true of the President when he stays in the nation's capital of Washington, D.C., and is host to a foreign leader.
On these special occasions, the national anthems of the United States and of the country represented by the foreign statesman are played.
National anthems were written as official patriotic songs. They are meant to stir patriotism and loyalty to one's country. Many of the world's anthems were written at times of war and other crises to give people a sense of belonging to their country.
The oldest anthem in the world is the anthem of the Netherlands. This Dutch anthem was written in the 16th century. It is called ''Wilhelmus van Nassouwe.'' Translated it means William of Nassau.
One of the most famous of world anthems is the British anthem ''God Save the Queen,'' or ''God Save the King'' if the monarch is a king.
Although it is well-known in many parts of the world, historians cannot make up their minds who definitely wrote it. Some think it was a Henry Carey in 1740. Others believe it was John Bull in 1619. Another possibility is James Oswald, a Scotsman who settled in London in 1745.
Many people regard it as the mother of anthems, since the music was adopted by several other countries. Switzerland had used this melody as its anthem, but changed it recently. Even the tune of the American patriotic song ''My Country Tis of Thee'' is taken from ''God Save the Queen.'' The same melody has often been used in classical music. Handel used it in his ''Occasional Oratoria'' and Beethoven in ''Wellington's Victory.''
There seems to have been a lot of borrowing when it comes to national anthems. The famous composer Joseph Haydn originally wrote a tune to be used for the national anthem of Austria. In 1922 Germany took the music for its national anthem, which was ''Deutschland, Deutschland, uber alles.'' (Germany, Germany, before everything.)
Next door in France the anthem played at ceremonious occasions or public gatherings is the ''Marseillaise.'' It was written by Claude Joseph Rouget de Lisle during the French Revolution, which lasted from 1789 to 1795. In July 1792 a battalion of volunteers from the important French seaport of Marseilles sang the song as they marched into Paris. And that's how the French anthem got its name.
It is not unusual for countries to change their anthems. The United States has done this. At the turn of the 19th century, our national anthem was ''Hail Columbia.''
The national anthem we know today was written during the War of 1812 with Britain. In 1814 Francis Scott Key, a Baltimore lawyer, was sent to the British fleet anchored off Fort McHenry outside Baltimore. He was sent to arrange the release of an American doctor who was being held prisoner on one of the British ships. On the night of Sept. 13, 1814, while he was on board a British ship, the British attacked Fort McHenry. All night long he watched the attack. At dawn he could still see the American flag flying over the fort. He was so moved by the experience that he wrote the words of ''The Star-Spangled Banner'' on an envelope.
The day after the battle he went to a tavern in Baltimore where a singer sang the words to the tune of an English song, ''To Anacreon in Heaven,'' which Key had chosen. It was made the official national anthem by an act of Congress on March 3, 1931.
Here are the words:
Oh say! Can you see, by the dawn's early light,
What so proudly we hailed at the twilight's last gleaming?
Whose broad stripes and bright stars through the perilous fight
O'er the ramparts we watched were so gallantly streaming?
And the rockets' red glare, the bombs bursting in air.
Gave proof through the night that our flag was still there.
Oh say does that star-spangled banner yet wave
O'er the land of the free and the home of the brave?