Tracery, on walls and windows, is mostly a feature of High Gothic and Late Gothic architecture, although there are some interesting examples from earlier periods, especially in the architecture of Islam, Visigothic and Mozarabic Spain, Early Christian Italy, and Byzantium.  In other periods, windows lack tracery altogether (for instance, there is no Romanesque window tracery).  Early Gothic narrow pointed windows (called lancets) also lack tracery.

Gothic tracery was done in two ways:
1) plate tracery:  the elements of glass are set in a solid stone framework.
2) bar tracery:  stone elements (mullions) are set in a large opening (a pointed lancet or rose), and glass is set within the mullions.

Tracery motifs: rose, trefoil, quatrefoil, cinqfoil, sexfoil, cusp, teardrop (mouchette) made of curvilinear elements; geometrical forms made of rectilinear elements.  Flower forms, characteristic of High Gothic tracery, are characterized in English architecture as 'decorated' and in French as 'rayonnant'; geometrical forms in Late Gothic are characterized in English architecture as 'perpendicular' (because the elements are generally rectilinear and rise perpendicular to the base of the window); curvilinear motifs in French and Italian Late Gothic are characterized as 'flamboyant' (because they are generally made up of flame-shaped elements or mouchettes).
 
 

Early Christian stucco infilling: Sta Sabina, Rome	Sta Sabina, Rome	Sta Sabina, Rome	Byzantine infilling: Gracanice,  Serbia
Visigothic tracery: Oviedo, Spain	Mozarabic tracery:  Sta Maria de Escalada, Spain	plain lancet with  hood moulding	Ripon Cathedral lancets in  west window
'Five Sisters' lancets York Minster,  north transept	diagram of plate tracery	Chartres Cathedral: three lancet windows (c. 1145) plate tracery rose (after 1194)	San Zeno, Verona Wheel of Fortune  window c. 1200
bar tracery  (decorated or rayonnant)	cusp	lancets with  trefoil tracery above	lancets with  trefoils and a rose above
mullions with trefoils above	cusped lancets with cinqfoils  and geometrical rose above	cusped lancets with  quatrefoils above (decorated or rayonnant)	Saint-Germain-en-Laye cusped lancets  with rose tracery above
Paris, sainte-Chapelle, interior arcading: cusped lancet  motifs with quatrefoils above	Metz Cathedral: large lancet window enclosing small  cusped lancets, quatrefoils, and a rayonnant rose	Westminster Abbey southe transept decorated rose	Prague Cathedral rayonnant rose
flamboyant rose	Paris, Sainte-Chapelle flamboyant rose	Milan Cathedral flamboyant rose	Seville Cathedral Late Gothic rose (combines rayonnant and flamboyant elements)
Alençon flamboyant tracery	Bath Abbey perpendicular tracery	.  Bath Abbey fan vaulting and perpendiculat tracery	Worchester Cathedral chantry chapel: perpendicular tracery
Kenilworth Castle perpendicular tracery	Cambridge, King's College Chapel: perpendicular tracery	Wells Cathedral net vault and perpendicular tracery