What is the difference between the verbs "ser" and "estar" in Spanish? (Both are "to be")

While both verbs mean "to be", and are used in descriptions, they are both used in different situations. "Ser" is used in the case of adjectives and descriptions that will not change in a short period of time, such as "yo soy inglesa" (I am British. Nationality is not likely to change.). It is also used when designating the time events will take place: "la reunión es el jueves" (The meeting is on Thursday). In this last case, you can replace the verb "ser" with "tener lugar" (To take place). "Estar" on the other hand, is used for temporary descriptions, or descriptions which may change: "él está enfermo" (he is ill. The expectation is he will get better). It is also used when talking about where the subject is at the time, so for example "yo estaré en casa por la tarde" (I will be home this afternoon).