Are These Stamp Blocks?

I can't seem to obtain a proper definition of stamp block, whether it be a plate block or just a block with no plate number. Does a block have to have a white border on at least two sides? Is there a specific number of stamps that is considered a block for each stamp issue? Are all the stamps in the photo considered blocks?

All are blocks with the exception of he strip of 8
A block does no have to have any space around it. There are different kinds of blocks, but a "block of 4" is just four stamps. On your picture you show a "Mr. ZIP block of 4" and also some larger blocks. The larger blocks that you show are plate blocks. Plate blocks used to be blocks of four in the good old days but with the use of multiple plates they can get very large.


Peter

Thanks for the answer Peter.

A "block" is four or more stamps still joined together in pairs, two on top, two on bottom. There are also blocks of six, eight, and so on. Or they can be blocks with three across, four across, and so on. Uneven numbers don't make a block, but just remove the single stamp and it becomes a block. Strips of stamps are not blocks.

Blocks with selvage (the white paper on the edges) help strengthen the block so it doesn't rip apart, but the selvage isn't necessary to call it a block.

A block with plate printing numbers on the selvage is called a "plate block". They used to be sought after and valuable, but not as much anymore. A block with Mr. Zip in the margin is called a "Zip block" but these are not much collected, I think.

For nearly all modern issues, there isn't anything especially valuable about a block. They're normally worth 4x the value of a single stamp which makes sense. Older (pre WWII) blocks have some additional value as blocks.

A block of more than four also isn't especially valuable, and it may be easier to mount a block of four than a larger block. How many do you need attached, really? A constant problem with blocks is that they seem to want to separate, especially if they're bent or handled a lot.