Lithuanian coat of arms, known as the Vytis, depicts a mounted soldier with raised sword on a red field. Dating back to the Grand Duchy of Lithuania it is among the Europe's oldest emblems. Atypically its source is Grand duke's seal rather than a dynastic coat of arms.
As the Grand Duchy spanned far beyond modern Lithuania the Vytis inspired many other symbols. Between 1991 and 1994 it (in a slightly different form) served as the coat of arms of Belarus and it is also included in some municipal and regional coats of arms in Poland.
A flag with Vytis had also been used in the Grand Duchy but today it is designated "Historic flag" and is masted only in a few historically important places.
Modern Lithuanian flag is a 20th century creation. As the reestablished Lithuanian state (1918) was a republic a tricolor design was adopted. Since the French Revoution (1789) most European republics used similar flags.
Lithuanian anthem "Tautiška giesmė" (National hymn) has been created in 1898 by Vincas Kudirka, one of the heroes of Lithuanian National Revival (adopted in 1920). It is notable for having each verse to follow a different melody and therefore should never be shortened (trimming the anthem in some sports events triggers discontent). A peculiar tradition calls every Lithuanian to sing the anthem on July 6th.
by Vincas Kudirka
Lietuva, Tėvyne mūsų,
Tegul Tavo vaikai eina
Tegul saulė Lietuvoj
Tegul meilė Lietuvos
English translation ©Augustinas Žemaitis.
Lithuania, our homeland,
May your children follow
May the sun over Lithuania
May the love of Lithuania
Before World War 2 and the subsequent Soviet genocide there were actually two Lithuanias. Current Catholic Lithuania-proper had sister Lithuania Minor which had been ruled by German states throughout most of its post-medieval history. Lithuania Minor had its own symbols which predated modern Lithuanian ones: a tricolor flag dating to 1660 and an anthem by Jurgen Sauerwein "Lietuvininkais mes esam gimę" ("Lietuvininks we are born" 1879).
Other symbols strongly associated with Lithuania are the Columns of Gediminas (or Pillars of Gediminas) and the Cross of Jogaila (a.k.a. Cross of Vytis), both named after medieval Lithuanian rulers. They are repeatedly used in many other symbols. For instance Cross of Jogaila forms a part of Lithuanian Coat of Arms and the air force ensign whereas the Pillars of Gediminas were used for the trademark of Eurobasket 2011 event held in Lithuania and political party symbols.
In Dzūkija where there is a strong presence of Polish speakers ethnic Lithunians traditionally erect crosses of Jogaila instead of traditional crosses in churchyards and roadsides to signify their ethnicity.
Other things and practices held as "national" by significant parts of society (none of these - except for language - are enshrined in law so its purely traditional):
National bird: White stork (ciconia ciconia)
National tree: Oak
National flower: Rue
National language: Lithuanian
National religion: Roman Catholicism
National sport: Basketball
National meal: Cepelinai (a.k.a. Didžkukuliai)
National alcoholic beverage: Beer
National "mineral" (jewelry): Amber
National saints: St. Casimir and St. George
Bird/tree/flower are based on their prevalence in folklore. Sport/religion/language are the most popular ones, followed by the majority of population. Meal/beverage/mineral are based on popular opinion. Saints are recognized by the Catholic crurch.