Most tourists and visitors to Egypt can obtain its an entry visa at any ports of entry. All foreigners arriving in Egypt should have a valid passport (with at least 6 months left before expiry) to get your entry visa.
However the entry visa can also be obtained from Egyptian Diplomatic and Consular Missions abroad or when in Egypt ( for extension or renewal) from the visa department at the Travel Documents Immigration and Nationality Administration (TDINA) at Mogamma building located at Tahrir squire in Cairo city centre.
There are 2 types of Egypt Visa:
Residence Visa: is required for any foreigner arriving in Egypt for purposes other than tourism e.g. work study etc. The possession of a valid entry visa is needed to complete the residence procedure in Egypt.
Tourist Visa: is usually valid for a period not exceeding one month granted on either single or multiple entry basis.
Egypt Entry Visa is valid only for travel within three months from the date of issue and is valid only for One- month stay in Egypt beginning on the date of arrival.
If you have a reason to extend your stay you can do that from the ministry of interior affairs in Egypt after declaring the reasons for that and their acceptance for that reasons.