【Flag】 ,  【ensign】 ,  【standard】 ,  【banner】 ,  【color】 ,  【streamer】 ,  【pennant】 ,  【pendant】 ,  【pennon】 ,  【jack】  are not always clearly distinguished.

【Flag】 , the comprehensive term, is applied to a piece of cloth that typically is rectangular, is attached to a staff, mast, halyard, or line, and carries an arrangement of colors, an emblematic figure, or a motto. The purpose of a 【flag】 is primarily to serve as a sign or symbol of a nation, a branch of the service, an organization, or an office, but it may also serve as a signal (as in military or naval operations) or in giving information (as of a weather change or the approach of a train).

【Ensign】 is applied chiefly to a 【flag】 that indicates nationality and specifically to one flown by ships at sea.

【Standard】  and  【banner】  are more or less literary terms for the 【flag】 (as of a country, a party, or a religious, civic, or patriotic organization) thought of as a rallying point or as something to be followed.

【Standard】 especially suggests the former because the term originally designated and still often designates a 【flag】 or a sculptured figure raised on a pole so as to be a gathering point for all who belong under it.

【Banner】 basically applies to a 【flag】 (often hung downward from a crosspiece instead of flying from a staff) of an individual (as an emperor, king, lord, or military leader) which was formerly flown from windows or doors or carried aloft at the head of a procession (as of troops marching to war).

【Color】  (most frequently found in the plural colors ) may apply to a national 【flag】 , to a 【flag】 emblematic of affiliation or partisanship, or to a 【flag】 of most military units; the term is particularly likely to suggest military activity or display.

The remaining terms are highly specific and definite in implications.

【Streamer】  applies to a long narrow 【flag】 (as on the masthead of a government ship) that floats in the wind;  【pennant】  and  【pendant】 , the latter more English than American, apply to a 【streamer】 that is long, narrow, and tapering.  【Pennant】  even more often applies to a narrow 【flag】 , typically triangular, which is flown by ships, which is used in signaling and in decorating, or which is exhibited (as by a baseball club) as a sign of championship.

【Pennon】  may apply to a narrower 【flag】 or a small 【streamer】 suitable for attaching to a lance.  【Jack】  denotes a small oblong 【flag】 indicating nationality which is hoisted on a staff at the bow or bowsprit cap of a ship or one used in signaling.