That sounds interesting! Stamps from the period 1874 to 1900, especially from Hungary, can be very valuable indeed, depending on their condition, rarity and historical significance. Here are some tips and general information to help you assess and understand your collection:

### Tips for Appraising Old and Valuable Stamps

1. **Condition**:
   - **Unused**: Stamps that have never been used, without cancellations or postmarks, are often more valuable.
   - **Use**: Used stamps can also be valuable, especially if the cancellation is interesting or rare.
   - **Damage**: Cracks, stains or other damage significantly reduce the value.

2. **Rarity**:
   - **Issue Edition**: The fewer copies of a particular stamp were printed, the more valuable it can be.
   - **Errors**: Stamps with printing errors or deviations can be very valuable due to their rarity.

3. **Historical Significance**:
   - Stamps that represent an important historical event or a special period may be worth more.

### Hungarian Postage Stamps (1874-1900)

The stamps from Hungary in the period mentioned can be divided into different categories:

1. **Austrian-Hungarian Period**:
   - Until 1871, postage stamps of the Austrian Empire were used in Hungary. From 1871, Hungary started issuing its own stamps, although it was still under Austrian rule.
   - **Examples**: The first Hungarian postage stamps, issued in 1871, with the portrait of Emperor Franz Joseph.

2. **Hungarian Kingdom**:
   - From 1867, after the Austro-Hungarian Compromise, Hungary gained more autonomy. The stamps from this period reflect these changes.
   - **Examples**: Stamps with the Hungarian coat of arms or portraits of Hungarian monarchs.

### Value of Stamps

The value of stamps can vary greatly. Here are a few steps you can take to get a better idea of ​​value:

1. **Catalogues**: Use stamp catalogs such as the Michel, Scott or Stanley Gibbons catalogs to get an idea of ​​the catalog value of your stamps.
2. **Experts**: Have your stamps assessed by a recognized stamp dealer or an expert. They can give you an accurate estimate.
3. **Online Marketplaces**: Check online auction sites like eBay to see what prices similar stamps are selling for.

### Conclusion

Old and valuable Hungarian stamps can be a fascinating collector's item and potentially of considerable value. Make sure you store them properly and consider having them appraised by an expert to accurately determine their value and rarity.